Assam is the largest state of the north-eastern region of India and is often called the gateway to the Seven Sister states. It lies roughly between 24° N and 28° N latitude and between 89° E and 96° E longitude. The state covers an area of 78,438 square kilometres, which is about 2.4 per cent of the total area of India. Assam is connected with the rest of the country through the narrow Siliguri corridor, also called the Chicken's Neck, in West Bengal.

Boundaries of Assam:

• To the north: Bhutan and Arunachal Pradesh.
• To the east: Nagaland and Manipur.
• To the south: Meghalaya, Tripura, Mizoram and a stretch of international boundary with Bangladesh.
• To the west: West Bengal and Bangladesh.

Assam therefore has two international neighbours, Bhutan and Bangladesh, and touches seven Indian states. Among all the north-eastern states, Assam is centrally placed and every other north-eastern state except Sikkim can be reached only through Assam by road. This is why Assam is called the heart of the north-east.

Physiographically, Assam is a land of valleys surrounded by hills. The mighty Brahmaputra and its tributaries drain the broad Brahmaputra valley in the north; the Barak river system drains the narrow Barak valley in the south; and between the two valleys lies a belt of hills and plateaus made up of the Karbi Anglong plateau, the Dima Hasao (North Cachar) hills and the ranges along the southern border. To the north the state is guarded by the foothills of the eastern Himalayas. Assam is thus almost completely surrounded on three sides by hills and mountains and opens only towards the west, through which the rain-bearing monsoon winds enter the valley.

Key points to remember:

• Assam lies between roughly 24°N–28°N latitude and 89°E–96°E longitude.
• The total area of Assam is 78,438 square kilometres (about 2.4% of India).
• Assam is the largest state of the north-east by area.
• Assam is connected to mainland India through the Siliguri corridor in West Bengal.
• International neighbours of Assam: Bhutan and Bangladesh.
• Indian states bordering Assam: Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Meghalaya and West Bengal.
• Assam is surrounded by hills on three sides and opens only to the west.
• The three natural divisions are the Brahmaputra valley, the Barak valley and the central hill-and-plateau belt.

For the purpose of administration, Assam is divided into five revenue divisions and, since 2022, 35 districts. Each division is looked after by a Divisional Commissioner, while each district is administered by a Deputy Commissioner. Below the district come the sub-divisions, revenue circles, mouzas and villages, and for urban areas there are municipalities and town committees.

The five administrative divisions of Assam with their headquarters:

• Lower Assam Division — headquarters Guwahati.
• North Assam Division — headquarters Tezpur.
• Central Assam Division — headquarters Nagaon.
• Upper Assam Division — headquarters Dibrugarh.
• Hills and Barak Valley Division — headquarters Diphu (created in 2015-16).

How the number of districts grew: Assam had only 27 districts till 2015. Between 2015 and 2022 the number was raised to 35. The important new districts are Biswanath, Charaideo, Hojai and South Salmara-Mankachar, the river-island district Majuli and West Karbi Anglong, and finally Bajali and Tamulpur in 2022. Majuli, formed out of the river island of the same name, became a full district in 2016 and is famous as the largest river island in the world.

Autonomous councils of Assam: Under the Sixth Schedule of the Constitution, three autonomous councils protect the interests of the tribal people:

• The Bodoland Territorial Region (BTR), earlier called Bodoland Territorial Area Districts (BTAD), with headquarters at Kokrajhar. It covers the four districts of Kokrajhar, Chirang, Baksa and Udalguri.
• The Karbi Anglong Autonomous Council, with headquarters at Diphu.
• The Dima Hasao Autonomous Council (the old North Cachar Hills), with headquarters at Haflong.

Some useful district facts for exams: Nagaon is the most populous district, while Kamrup Metropolitan (Guwahati) has the highest density of population and is the most urbanised. Karbi Anglong is the largest district by area and Majuli is the smallest district by population. Guwahati is the largest city and the commercial capital, while Dispur in Guwahati is the state capital.

Key district headquarters to remember: Kamrup Metropolitan – Guwahati (Dispur); Kamrup (rural) – Amingaon; Sonitpur – Tezpur; Nagaon – Nagaon; Morigaon – Morigaon; Dibrugarh – Dibrugarh; Tinsukia – Tinsukia; Jorhat – Jorhat; Sivasagar – Sivasagar; Golaghat – Golaghat; Cachar – Silchar; Karbi Anglong – Diphu; Dima Hasao – Haflong; Kokrajhar – Kokrajhar; Dhubri – Dhubri; Lakhimpur – North Lakhimpur; Darrang – Mangaldai.

Key points to remember:

• Assam has five revenue divisions and 35 districts (as of 2022).
• The five divisions are Lower Assam, North Assam, Central Assam, Upper Assam and Hills and Barak Valley.
• Division headquarters: Guwahati, Tezpur, Nagaon, Dibrugarh and Diphu.
• Majuli is a river-island district and the largest river island in the world.
• Bajali and Tamulpur are the two newest districts (2022).
• The Bodoland Territorial Region covers Kokrajhar, Chirang, Baksa and Udalguri.
• Karbi Anglong and Dima Hasao are the two hill districts with autonomous councils.
• Nagaon is the most populous district; Kamrup Metropolitan is the most densely populated.
• Karbi Anglong is the largest district by area; Majuli is the smallest by population.
• Dispur (in Guwahati) is the state capital of Assam.

The relief of Assam has been shaped mainly by the two great rivers, the Brahmaputra and the Barak, and by the hill systems that surround the state. Geologically, the Brahmaputra valley is a great alluvial trough that lies between the rising Himalaya in the north and the old Meghalaya plateau in the south. On the basis of relief, Assam is divided into three broad physiographic divisions:

1. The Brahmaputra valley plains: This is the largest natural division of Assam. It stretches from Sadiya in the east to Dhubri in the west, a length of roughly 700 kilometres, and its width varies from about 20 kilometres near Guwahati to about 100 kilometres in parts of the north bank. The valley is built of very fertile new and old alluvium brought down by the Brahmaputra and its tributaries. The river itself is braided and constantly changes its course, leaving behind sand-bars (chars) and river islands, of which Majuli is the largest. On the north the valley is bounded by the foothills of the eastern Himalayas and on the south by the Meghalaya and Nagaland hills.

2. The central and southern hill-and-plateau region: In the middle of the state lie the Karbi Anglong (Mikir) plateau and the Dima Hasao (North Cachar) hills, which together are a detached part of the great Shillong plateau. This is an old, hard, rocky land of denuded hills, flat-topped plateaus, deep gorges and waterfalls. The highest elevations of Assam are found in this region; the highest point, about 1,959 metres above sea level, lies in the Borail (Barail) range of Dima Hasao district. The Kopili river, the largest south-bank tributary of the Brahmaputra, cuts its way through this hill region.

3. The Barak valley plains: In the far south, beyond the Barail and other ranges, lies the narrow but fertile Barak valley, made up of the plains of the old Surma valley (the present districts of Cachar, Karimganj and Hailakandi). This low-lying plain receives very heavy rain, is drained by the Barak and its tributaries and is covered with fertile clayey alluvium. The valley is bounded on the south by the hills of Mizoram and on the east by the Manipur hills.

In short, the physical make-up of Assam may be remembered as: high mountains in the north (beyond the state border), the wide alluvial Brahmaputra plain in the middle, the old plateau-and-hill country of Karbi Anglong and Dima Hasao, the long southern ranges, and the small Barak plain at the far south. Rivers dominate the landscape; flood plains, sand-bars, river islands, beels and ox-bow lakes are the typical landforms of the plains, while gorges, waterfalls and narrow valleys are typical of the hill country.

Key points to remember:

• Assam has three broad physiographic divisions: the Brahmaputra valley, the middle hill-and-plateau region, and the Barak valley.
• The Brahmaputra valley extends roughly from Sadiya to Dhubri, over about 700 km.
• The Brahmaputra valley is a great alluvial trough between the Himalaya and the Meghalaya plateau.
• Karbi Anglong plateau and Dima Hasao hills are a detached part of the Shillong plateau.
• The highest point of Assam (about 1,959 m) lies in the Borail range of Dima Hasao.
• The Kopili is the largest south-bank tributary of the Brahmaputra.
• The Barak valley is the old Surma valley, made up of Cachar, Karimganj and Hailakandi.
• Typical landforms of the plains are chars, river islands, beels and ox-bow lakes.
• The Brahmaputra river is braided and constantly changes its course.

The Brahmaputra is one of the mightiest rivers of the world and the lifeline of Assam. It is older than the Himalaya itself and carries a greater volume of water than almost any other river of the world. It rises from the Chemayungdung glacier of the Kailash range in southern Tibet, not far from the sources of the Indus and the Sutlej. In Tibet the river is called the Tsangpo, and it flows eastward for a very long distance parallel to the Himalaya. In total the Brahmaputra travels about 2,900 kilometres before it reaches the sea.

The course of the river: From Tibet the river enters India through Arunachal Pradesh, where it is called the Siang or Dihang. In Arunachal it is joined by the Dibang and the Lohit, and after these two rivers meet it near Kobo in the Sadiya region of Assam, the combined stream becomes the Brahmaputra. The river then flows westward across the whole breadth of Assam for about 640 kilometres. Near Guwahati, at Saraighat, it narrows down to about one kilometre, the narrowest point of its journey in Assam. From there it turns south, enters Bangladesh and is called the Jamuna. In Bangladesh it joins the Ganga (Padma) and the combined waters finally flow into the Bay of Bengal through the Meghna estuary.

Characteristics of the Brahmaputra in Assam: The river is braided — it breaks into many channels that keep changing — and it is constantly shifting its course. It deposits enormous loads of silt and sand, forming sand-bars (chars), islands and shifting banks. This makes the river difficult to tame; almost every year it causes floods and erosion. The most famous river island, Majuli, lies in the Brahmaputra between its main channel and its northern branches. The river is also important as a waterway; the stretch from Sadiya to Dhubri (about 891 km) has been declared National Waterway 2.

Main tributaries of the Brahmaputra:

• North-bank (right-bank) tributaries: Subansiri, Ronganadi, Dikrong, Jiabharali, Puthimari, Pagladiya, Manas, Beki, Aie, Champamati, Saralbhanga and Sankosh. Of these, Subansiri is the largest tributary of the Brahmaputra, and Manas is a major river which rises in Bhutan.
• South-bank (left-bank) tributaries: Noa Dehing, Buri Dihing, Disang, Dikhou, Bhogdoi, Dhansiri, Kopili, Kulsi, Krishnai and Dudhnoi. Kopili is the largest south-bank tributary; it cuts through the hill region of Karbi Anglong and Dima Hasao.

The major tributaries that the Ahoms and the modern administration have used as boundaries, and the rivers on whose banks the important towns stand, are best learnt with a map. Remember: Dibrugarh, Guwahati and Dhubri stand on the Brahmaputra; Tezpur stands on the Jia Bharali; Jorhat is watered by the Bhogdoi; and Silchar stands on the Barak.

Key points to remember:

• The Brahmaputra rises from the Chemayungdung glacier of the Kailash range in Tibet.
• In Tibet it is called the Tsangpo; in Bangladesh it is called the Jamuna.
• It enters India through Arunachal Pradesh as the Siang (Dihang).
• After the Dibang and the Lohit join it near Kobo (Sadiya), it becomes the Brahmaputra.
• The Brahmaputra flows about 640 km through Assam.
• The narrowest point of the river in Assam is at Saraighat, Guwahati (about 1 km).
• Subansiri is the largest tributary of the Brahmaputra; Manas rises in Bhutan.
• Kopili is the largest south-bank tributary of the Brahmaputra.
• The Brahmaputra from Sadiya to Dhubri (about 891 km) is National Waterway 2.
• Majuli, the world's largest river island, lies in the Brahmaputra.

The Barak is the principal river of southern Assam and gives its name to the whole Barak valley. It rises in the Barail (Borail) range of the Manipur hills and enters Assam through the district of Cachar. The total length of the Barak is about 900 kilometres, of which only a part flows through Assam. Near the Bangladesh border the river splits into two branches, the Surma and the Kushiyara; further south these join the waters of the Ganga, and the combined river, known as the Meghna, falls into the Bay of Bengal. The southern part of old Assam was therefore historically called the Surma valley.

The Barak valley is the smaller of the two great valleys of Assam. It is made up of the three districts of Cachar, Karimganj and Hailakandi and is separated from the Brahmaputra valley by the high ridges of the Meghalaya plateau, the Barail range and the North Cachar (Dima Hasao) hills. The valley is open towards Bangladesh and Manipur, which makes it an important gateway for trade with those areas. It is a low, flat, very wet plain which receives some of the heaviest rainfall in India, and its soil is fertile clayey alluvium. The principal town of the valley is Silchar, the headquarters of Cachar district and an important commercial and railway centre of south Assam.

Agriculture and economy of the valley: The Barak valley is famous for its tea gardens (especially in Cachar), its winter rice and its jute. Karimganj is a well-known jute-producing district. The valley also produces sugarcane, pulses, oilseeds and many fruits. Fishing is important in its beels and rivers. Because the valley remains green and wet almost all the year, it is sometimes called the 'green valley' of Assam.

Main tributaries of the Barak: The important tributaries of the Barak within Assam are the Jiri, Chiri, Madhura, Jatinga, Larang, Sonai and Longai. Among these, the Jatinga river in Dima Hasao district is world-famous for a strange natural mystery — every year, during a particular season, many birds are found to fall down near the Jatinga village, a phenomenon popularly called the 'Jatinga bird mystery'. The valley is also connected to the Brahmaputra valley by the Lumding–Silchar railway line, which passes through the hills, and by road through the Jatinga and other passes.

Key points to remember:

• The Barak rises in the Barail range of the Manipur hills.
• It gives its name to the Barak valley of southern Assam.
• The total length of the Barak is about 900 km.
• In Bangladesh it splits into the Surma and the Kushiyara and finally joins the Meghna.
• The Barak valley consists of Cachar, Karimganj and Hailakandi districts.
• The old name of the southern plains region is the Surma valley.
• The Barak valley receives very heavy rainfall and has fertile clayey soil.
• Silchar, on the bank of the Barak, is the headquarters of Cachar district.
• Important tributaries: Jiri, Chiri, Madhura, Jatinga, Larang, Sonai and Longai.
• The Jatinga valley is famous for the mysterious bird-suicide phenomenon.
• The valley is a gateway to Bangladesh, Mizoram, Tripura and Manipur.

Assam has a tropical monsoon climate with high humidity, but because the state is sheltered between hills and receives the cooling rains of the monsoon, its temperatures are neither too high in summer nor too low in winter. The two most important controls of Assam's climate are the south-west monsoon and the local relief (hills and valleys). There is no distinctly dry and hot summer as in the plains of northern India, and no severe winter.

Seasons of Assam:

1. The winter season (December to February): The weather is cool and generally dry. Light rain may fall from the north-east monsoon, and the hills experience mist and fog. January is the coldest month; the average temperature in the plains in winter is between about 8°C and 15°C.

2. The pre-monsoon season (March to May): This is the hottest part of the year, though temperatures rarely cross about 38°C. In the late afternoon and evening there are violent thunderstorms with strong squally winds, locally called Bordoisila (the storm of the pre-monsoon season), which often bring hail. These storms are welcome because they give rain before the main monsoon.

3. The south-west monsoon season (June to September): This is the main rainy season of Assam. The monsoon winds enter the state from the south-west and pour most of the year's rainfall. About 70–75 per cent of the total annual rain falls in these four months. Heavy rain continues longest over the Barak valley and the southern hills.

4. The retreating monsoon season (October to November): Rain decreases quickly, the skies clear, and the weather becomes pleasant. Sometimes cyclonic storms from the Bay of Bengal bring unseasonal rain.

Rainfall and temperature: The average annual rainfall of Assam is high (about 2,500 mm) and it increases towards the surrounding hills. The Barak valley, the Dima Hasao hills and the south-facing slopes receive the heaviest rain, while some parts of the middle Brahmaputra valley receive comparatively less. Among the well-known wet places, the region around Silchar and the southern hills receives far more rain than Guwahati and the central valley. Humidity remains high for most of the year, and the climate as a whole is moist, warm and favourable for tea, rice and dense forests.

Effects on life and economy: Because the rains come with the monsoon, the whole agriculture of the state — the ahu, sali and boro paddy, tea and jute — depends on the timing of the rains. A weak or late monsoon causes drought-like conditions, while a very strong monsoon causes floods. On the whole the warm, humid climate of Assam supports its evergreen forests, its wildlife and its two-crop agriculture.

Key points to remember:

• Assam has a tropical monsoon climate with high humidity.
• The climate is controlled mainly by the south-west monsoon and by the local relief.
• Assam has four seasons: winter, pre-monsoon (summer), south-west monsoon and retreating monsoon.
• January is the coldest month and the pre-monsoon period (March–May) is the hottest.
• The local pre-monsoon thunderstorm of Assam is called Bordoisila.
• About 70–75% of the annual rain falls during the south-west monsoon (June–September).
• The average annual rainfall of Assam is about 2,500 mm.
• The Barak valley and the southern hills receive the heaviest rainfall.
• Temperatures in Assam are moderate and never extreme.
• Agriculture, tea and forests all depend on the monsoon rains.

The soils of Assam are among the most fertile in India because they are mostly alluvial, brought down and renewed by the great rivers and their tributaries. The two valleys of the state, the Brahmaputra valley and the Barak valley, are covered by deep deposits of river-borne alluvium, while the hill and plateau regions carry soils formed from the weathering of rocks.

Main soil types of Assam:

1. New alluvial soil: Found on the recent flood-plains, chars and the low river banks of the Brahmaputra and the Barak. It is sandy to loamy, light in colour, very fertile and is renewed by every flood. It is best suited for rice, vegetables and jute.

2. Old alluvial soil: Found on the higher, older terraces and plains away from the rivers. It is finer, darker and more clayey than the new alluvium and contains more humus. It supports tea, rice, oilseeds and most of the valley crops.

3. Laterite soil: Found on the hill slopes and plateau tops of Karbi Anglong, Dima Hasao and the lower parts of the surrounding hills. It is red or reddish-brown, rich in iron and aluminium but poor in lime and humus. It becomes very hard when dry and needs manuring and irrigation.

4. Red and hill soils: Thin, stony soils found on the steep slopes of the hill districts; they are poor and easily eroded if the forest cover is removed.

5. Sandy and marshy soils: Sandy soils occur along the active river beds and chars; dark, water-logged, peaty soils are found around the beels, swamps and low-lying depressions of the valleys.

General characteristics: Because of heavy rainfall and leaching, most Assam soils are slightly acidic (sour) and are comparatively rich in organic matter and potash but poor in phosphate and lime. The valley alluvium is deep, loose and easy to cultivate, while hill soils are shallow. In the tea districts the soil is naturally well drained, which suits the tea plant. The floods, which cause so much damage, also bring fresh silt every year, and this is one reason the valley soils have remained fertile for thousands of years.

Soil and agriculture: The fertility of the alluvial soil allows two or even three crops of paddy (ahu, sali and boro), and supports jute in the Barak valley and lower Assam, sugarcane in several districts, and the famous tea gardens. In the hill and plateau areas, shifting cultivation (jhum) and the clearing of forests have caused soil erosion, so soil conservation — terracing, afforestation and bunding — is very important. For competitive exams remember that the soil of Assam is basically alluvial and acidic, and that the two valleys are its great granaries.

Key points to remember:

• Assam soils are mainly alluvial, formed by the rivers.
• New alluvium is found near the rivers on flood-plains and chars.
• Old alluvium covers the higher, older plains away from the rivers.
• Laterite soil is found in the Karbi Anglong, Dima Hasao and other hill areas.
• Red and thin hill soils occur on steep slopes.
• Sandy soils occur on river beds; peaty marshy soils occur near beels and swamps.
• Most Assam soils are acidic because of heavy rain and leaching.
• The soils are rich in organic matter and potash but poor in phosphate and lime.
• Fertile alluvial soil supports rice (ahu, sali, boro), jute, sugarcane and tea.
• Soil erosion is a problem in the hill areas; terracing and afforestation help conserve soil.

Because of its warm, humid climate, heavy rainfall and fertile soil, Assam is naturally a land of lush green vegetation. Almost every part of the state, except the cultivated fields, is covered with dense forest, bamboo brakes, grassland or swamp vegetation. According to the Forest Survey of India (2021), the forest cover of Assam is about 36 per cent of its total area, and a large part of this is open forest. A very high proportion of the state's recorded forest area lies on the north bank and in the hill districts.

Main types of forests of Assam:

1. Tropical evergreen and semi-evergreen forests: These grow in the areas of very heavy rainfall — the southern slopes and valleys of the Dima Hasao and Karbi Anglong hills and parts of the upper Brahmaputra valley. The trees remain green throughout the year. Important species include hollong, nahor, gurjan, ajhar and other tall timber trees, together with creepers, canes and many orchids.

2. Moist deciduous forests: These are the most widespread forests of the middle and lower parts of the state. The trees shed their leaves for a short period in the dry season. Sal is the most important tree of these forests, along with khair, sissoo and simul (silk-cotton).

3. Riverine forests: These grow along the banks and islands of the Brahmaputra and its tributaries. The trees and bushes here, such as khair and sissoo, resist flood and silting.

4. Grasslands and savannah: On the flood-plains, especially around Kaziranga, Orang and Manas, there are tall elephant-grass meadows and reed-beds (ekra), which shelter the rhino, the tiger and many grazing animals.

5. Swamp forests and wet bamboo brakes: Around the beels and marshy depressions grow water-loving trees and dense clumps of bamboo and cane.

Bamboo, canes and other wealth of the forests: Assam is one of the richest states of India in bamboo and cane. Bamboo is used for building, baskets, furniture, paper and even as food (young shoots), and it supports many handicrafts and small industries. The forests also provide valuable timber (hollong is the tallest of the great trees of the region), medicinal herbs, honey, resin and a home to the famous orchids of the north-east, including the kopou phool (the state flower of Assam).

Forests and conservation: The forests protect the soil, regulate the flow of rivers and give shelter to wildlife. For this reason large areas have been declared reserved forests, national parks and wildlife sanctuaries. The main threats to the forests of Assam are the clearing of land for cultivation (including jhum or shifting cultivation in the hills), encroachment, and illegal felling of timber. To save the forests, the government promotes afforestation, social forestry and protection of the sanctuaries.

Key points to remember:

• Warm humid climate and heavy rain make Assam naturally rich in vegetation.
• The forest cover of Assam is about 36% of its total area (ISFR 2021).
• Main forest types: tropical evergreen/semi-evergreen, moist deciduous, riverine, grassland and swamp forests.
• Sal is the most important tree of the moist deciduous forests of Assam.
• Hollong and nahor are important trees of the evergreen forests.
• Kaziranga, Manas and Orang are famous for tall elephant grasslands.
• Assam is very rich in bamboo and cane resources.
• The kopou phool is the state flower of Assam.
• Bamboo supports many handicrafts and industries in the state.
• Jhum cultivation, encroachment and illegal felling are the main threats to forests.

Assam is one of the richest wildlife regions of the world. Its flood-plain grasslands, evergreen forests and wetlands shelter the one-horned rhinoceros, the tiger, the elephant, the wild water buffalo, the gaur, the sambar, the swamp deer, the hoolock gibbon (the only ape found in India), the golden langur, the capped langur, the clouded leopard and the white-winged wood duck (Deo hah), along with hundreds of species of birds, reptiles and fishes. Two natural areas of Assam — Kaziranga and Manas — are UNESCO World Heritage Sites, the only two natural World Heritage Sites of the whole of north-east India.

The state has seven national parks. Remember them as:

1. Kaziranga National Park (Nagaon and Golaghat districts, on the south bank of the Brahmaputra): declared a national park in 1974 and a World Heritage Site in 1985. It is world-famous for the one-horned rhinoceros, whose population here is now about 2,600; it is also a tiger reserve. The park is made up of elephant-grass meadows and wet forests.

2. Manas National Park (Baksa, Chirang and Kokrajhar districts): lying in the foothills of the Himalaya on the Manas river, it became a World Heritage Site in 1985, a biosphere reserve in 1989 and a tiger reserve. It is famous for the golden langur, the pygmy hog and the Assam roofed turtle, besides the tiger and the elephant.

3. Orang National Park (Darrang and Sonitpur districts, on the north bank): often called the 'Mini Kaziranga' of Assam because of its rhinos and tigers.

4. Nameri National Park (Sonitpur district, on the Jia Bharali river): famous for the tiger and the rare white-winged wood duck, with beautiful river-bank forests on the Assam–Arunachal border.

5. Dibru-Saikhowa National Park (Dibrugarh and Tinsukia districts): a forested river-island park between the Brahmaputra and the Dibru; famous for wild horses, the white-winged wood duck and wintering migratory birds. It is also a biosphere reserve.

6. Dehing Patkai National Park (Dibrugarh and Tinsukia districts): a lowland tropical rainforest along the Dehing river, declared a national park in 2020; rich in elephants, the hollong tree and rare orchids.

7. Raimona National Park (Kokrajhar district): the newest national park, created in 2021 near the Bhutan border; home to wild elephants, gaur and hornbills.

Important wildlife sanctuaries:

• Pobitora Wildlife Sanctuary (Morigaon): has the highest density of one-horned rhinos in the world and is known as the 'Mini Kaziranga'.
• Hollongapar Gibbon Wildlife Sanctuary (Jorhat): the only sanctuary named after the gibbon; protects the hoolock gibbon in its tall hollong forest.
• Panidihing Bird Sanctuary (Sivasagar): a wetland famous for thousands of wintering migratory birds.
• Chakrashila Wildlife Sanctuary (Kokrajhar): known for the golden langur.
• Deepor Beel (near Guwahati): a large natural wetland and a Ramsar site, rich in birds.

Three of the national parks — Kaziranga, Manas and Orang — are also tiger reserves. The state animal of Assam is the one-horned rhinoceros and the state bird is the white-winged wood duck (Deo hah). Wildlife protection is a major responsibility of the forest department, and the tall grasslands and beels of the Brahmaputra valley are the key to the survival of the rhino and the tiger.

Key points to remember:

• Assam has seven national parks and the state animal is the one-horned rhinoceros.
• Kaziranga and Manas are the two natural UNESCO World Heritage Sites of Assam.
• Kaziranga (1974) is world-famous for the one-horned rhino; it is also a tiger reserve.
• Manas is a World Heritage Site, biosphere reserve and tiger reserve; famous for the golden langur.
• Orang is called the 'Mini Kaziranga'; it lies on the north bank of the Brahmaputra.
• Nameri is famous for the tiger and the white-winged wood duck.
• Dibru-Saikhowa is a river-island park famous for wild horses and migratory birds.
• Dehing Patkai (2020) and Raimona (2021) are the two newest national parks.
• Pobitora has the highest density of rhinos; Hollongapar protects the hoolock gibbon.
• The white-winged wood duck (Deo hah) is the state bird of Assam.
• The tiger reserves of Assam are Kaziranga, Manas and Orang.

Assam is one of the most water-rich states of India. Besides the two great river systems of the Brahmaputra and the Barak, the state is dotted with hundreds of beels (wetlands), many streams, springs and a large store of groundwater. The whole economy — agriculture, fisheries, tea, transport and daily life — is built upon this water wealth.

The beels and wetlands: The changing courses of the rivers have left behind many shallow lakes, ox-bow lakes and marshy depressions, which the people of Assam call beels. These beels are the pride of the state. They store flood water, recharge groundwater, and support fish, water-birds and aquatic plants. Thousands of families earn their living by fishing in these beels. Some important beels and wetlands are:

• Deepor Beel, near Guwahati: the most famous wetland of Assam and a bird paradise. It was declared the first Ramsar site of Assam in 2002.
• Sone (Son) Beel in Karimganj district: the largest wetland of the Barak valley, famous for its seasonal fishing and migratory birds.
• Urpad Beel in Dhubri district: one of the largest seasonal beels of the Brahmaputra valley.
• Chandra Beel, Silsako Beel and several others in different districts are important local wetlands.

Ramsar sites of Assam: Deepor Beel was for a long time the only Ramsar site of Assam. In 2024 the government recognised four more wetlands of the state — Sone Beel, Urpad Beel, Chandra Beel and Silsako Beel — as Ramsar sites, taking the number of Ramsar wetlands of Assam to five. A Ramsar site is a wetland of international importance, named after the city of Ramsar in Iran where the international treaty on wetlands was signed.

Groundwater and drinking water: The plains of Assam have abundant and easily available groundwater, because the whole valley is made of thick layers of sand and alluvium that store rainwater. Tubewells and dug-wells supply most of the drinking water of the state. In the hill districts of Karbi Anglong and Dima Hasao, however, hard rock lies near the surface, and the people depend more on springs, streams and ponds. Floods make water supply difficult during the monsoon, and water quality is a problem in the flood-affected and urban areas.

Uses of water in Assam: Agriculture uses the largest share of water — the sali paddy depends on the monsoon and the boro paddy is grown with irrigation. The beels and rivers supply fish; the rivers provide cheap inland water transport, especially the Brahmaputra, which is National Waterway 2 from Sadiya to Dhubri. The hilly tributaries carry a huge hydro-electric potential, though only a part of it has been tapped so far. Wetlands also control floods and keep the river valleys healthy.

Key points to remember:

• Assam is one of the most water-rich states of India.
• The beels of Assam are shallow lakes and ox-bow lakes left by changing river courses.
• Deepor Beel near Guwahati was the first Ramsar site of Assam (2002).
• Sone Beel in Karimganj is the largest wetland of the Barak valley.
• Urpad Beel is a large seasonal beel of Dhubri district.
• In 2024, Sone Beel, Urpad Beel, Chandra Beel and Silsako Beel were added as Ramsar sites.
• Assam now has five Ramsar sites.
• The plains have abundant groundwater because the valley is made of thick sand and alluvium.
• The hill districts depend more on springs and streams for water.
• The Brahmaputra is National Waterway 2, used for inland water transport.
• Beels help in flood control, fisheries and groundwater recharge.

Assam is essentially an agricultural state. A very large part of the population depends directly on farming, and agriculture is the backbone of the state's economy. The fertile alluvial soil, the warm humid climate and the monsoon rain make the two valleys of Assam natural granaries.

Rice is the principal food crop and the staple food of the people. Assam grows three crops of paddy in a year:

1. Ahu (autumn paddy): sown in February–March with the help of pre-monsoon showers and harvested in June–July.

2. Sali (winter paddy): the main crop of Assam. It is sown in June–July with the beginning of the monsoon and harvested in November–December.

3. Boro (summer paddy): grown in low-lying areas and beels with the help of irrigation or stored water, sown in November–December and harvested in April–May.

Almost every district grows paddy, but the most important rice-growing areas lie in the north bank districts of Lakhimpur and Dhemaji, and in Nagaon, Sivasagar and Dibrugarh. Besides paddy, Assam produces maize, pulses, oilseeds such as mustard and rapeseed, potato, sugarcane and many vegetables. Mustard is the main oilseed and is grown widely in the winter.

Tea is the most important commercial crop of Assam. Assam is the largest tea-producing state of India and contributes about half of the country's total tea production. The tea gardens are found mainly in the Brahmaputra valley — especially in the districts of Dibrugarh, Tinsukia, Sivasagar, Jorhat, Golaghat, Nagaon and Sonitpur — and in the Barak valley (Cachar). The warm, moist climate, well-drained soil and heavy rain give the Assam tea its strong, brisk flavour. Most of Assam's tea is of the CTC type, and the state is famous as one of the greatest tea regions of the world.

Jute is another important cash crop, grown mainly in the Barak valley (especially Karimganj) and in the lower Brahmaputra districts such as Dhubri and Goalpara. Among plantation and horticultural crops, Assam is famous for bananas, pineapples, oranges (in the hill areas), litchi (Tezpur and its neighbourhood), areca nut and coconut. The hill districts grow citrus fruits and vegetables. Assam also has a large number of livestock — cattle, buffaloes, goats and pigs — and a big duck population; fish from the rivers and beels is an essential part of the Assamese diet.

Irrigation and the farmer's problems: Assam is largely a rain-fed farming area; only a small part of the cultivated land has assured irrigation. The farmers therefore depend on the mercy of the monsoon. Floods destroy standing crops every year, and erosion takes away fertile land, while in some years a weak monsoon brings drought. To improve farming, the government has been promoting better seeds, chemical and organic fertilisers, minor irrigation schemes, and schemes for the development of tea, horticulture and fisheries.

Key points to remember:

• Assam is an agricultural state and rice is its principal food crop.
• Assam grows three crops of paddy: ahu, sali and boro.
• Sali is the main (winter) crop; ahu is the autumn crop; boro is the summer crop.
• Assam is the largest tea-producing state of India, contributing about half of the country's tea.
• The main tea districts are Dibrugarh, Tinsukia, Sivasagar, Jorhat, Golaghat and Cachar.
• Jute is grown mainly in the Barak valley and in lower Assam.
• Mustard is the main oilseed of Assam.
• Litchi (Tezpur), oranges, pineapple and bananas are important fruit crops.
• Assam is largely rain-fed; only a small part of the land has irrigation.
• Floods, erosion and the uncertain monsoon are the main problems of Assamese farmers.

Assam has the proud distinction of being the pioneer state of India in the discovery of mineral oil. Its principal mineral resources are petroleum (crude oil), natural gas, coal and limestone, besides smaller quantities of clay, sand and stone used for building. Most of the valuable minerals are concentrated in Upper Assam, with limestone found in the hill districts.

Petroleum (mineral oil): Assam is the oldest oil-producing region of the country. In 1889 the first oil well of Asia was drilled at Digboi in the Tinsukia district, and in 1901 the Digboi refinery — the oldest operating refinery in the world — was set up there. The chief oil-fields of Assam are Digboi, Naharkatia, Moran, Rudrasagar, Lakwa and Geleki. The oil-fields lie mainly in the districts of Tinsukia, Dibrugarh and Sivasagar. The two public companies that produce oil and gas in Assam are the Oil India Limited (OIL), whose headquarters is at Duliajan, and the Oil and Natural Gas Corporation (ONGC).

Natural gas: Assam also holds large reserves of natural gas, found together with the oil. The gas is used by the fertilizer factory at Namrup, by several power plants and by the petrochemical industry. The Assam Gas Cracker Project — officially the Brahmaputra Cracker and Polymer Limited (BCPL) at Lepetkata near Dibrugarh — uses this gas to make plastic products, and is one of the biggest gas-based petrochemical units of the north-east. Gas is distributed to homes and industries through pipelines by the Assam Gas Company.

Coal: Assam's coal is tertiary coal, found mainly in Upper Assam. The most important coal-fields are the Makum coal-field (with the Ledo, Margherita and Tipong collieries) in the Tinsukia district and the Dilli–Jeypore coal-field. The coal is used in railways, brick-kilns, tea factories and thermal power plants.

Limestone: Good-quality limestone is found in the Karbi Anglong, Dima Hasao and Goalpara districts. It is the raw material of the cement factories of Assam, such as the plant at Bokajan (Karbi Anglong). Besides these, Assam has deposits of fire-clay, kaolin, glass-sand and granite, which support small brick, tile and stone industries.

Energy resources of Assam:

• Refineries: Assam has four oil refineries — the Digboi refinery (1901, the oldest), the Guwahati refinery at Noonmati (1962), the Bongaigaon refinery (1979) and the Numaligarh refinery (2000, the newest and largest). Together they make Assam one of the major petroleum-refining regions of the country.
• Thermal power: Electricity is generated at the Bongaigaon thermal power station, the Namrup thermal power station (gas-based) and the Chandrapur thermal power station near Guwahati.
• Hydro power: The main hydro-electric project of the state is the Kopili Hydro Electric Project on the Kopili river in the Dima Hasao hill district. Several small hydro projects also exist.
• New and renewable energy: Assam has begun to use solar energy, wind energy on a small scale and biomass energy, and their share in the state's power is increasing.

Key points to remember:

• Assam is the pioneer state of India in petroleum production.
• The first oil well of Asia was drilled at Digboi in 1889.
• The Digboi refinery (1901) is the oldest operating refinery in the world.
• Main oil-fields: Digboi, Naharkatia, Moran, Rudrasagar, Lakwa and Geleki.
• OIL India Limited has its headquarters at Duliajan.
• Assam has four refineries: Digboi, Guwahati (Noonmati), Bongaigaon and Numaligarh.
• Namrup has a gas-based fertilizer factory; BCPL at Lepetkata is the gas-cracker project.
• The main coal-fields are Makum (Ledo, Margherita, Tipong) and Dilli–Jeypore.
• Limestone is found in Karbi Anglong, Dima Hasao and Goalpara; Bokajan has a cement plant.
• The main hydro project is the Kopili Hydro Electric Project in Dima Hasao.

The economy of Assam is mainly agricultural, but industries are steadily growing. Assam's industries may be grouped into agro-based, forest-based, mineral-based and cottage industries. Among all industries, tea processing and petroleum refining are the largest, while the handloom and handicraft industries of the state are famous throughout India.

Agro-based industries: Tea is the biggest organised industry of Assam. The state has about 800 large tea estates with their own factories, and tea is processed into CTC and orthodox tea for the whole world. Around the tea gardens there are engineering workshops and tea-chest (plywood) units. Rice mills, flour mills, oil mills, sugar factories, jute mills and fruit-processing units form the other agro-based industries. The sugar factories of Assam work on locally grown sugarcane, and jute is processed mainly in the Barak valley and lower Assam.

Forest-based industries: Assam has a long tradition of using its forests. The important forest-based industries are saw-milling, plywood, paper and paper-board, and the making of cane and bamboo goods. The two large paper mills of the state were the Nagaon Paper Mill at Jagiroad (in Nagaon district) and the Cachar Paper Mill at Panchgram (in the Barak valley). Bamboo, cane, reed and timber from the forests support many small industries and thousands of craftsmen.

Sericulture and textiles: Assam is the home of the golden muga silk, which is produced nowhere else in the world in such abundance. Besides muga, the state produces eri silk and pat (mulberry) silk. The silk is reeled, spun and woven in every district, and the village of Sualkuchi, near Guwahati, is famous throughout India as a centre of fine silk weaving. The handloom of Assam is one of the largest of the country, and nearly every Assamese home has a loom. The Assamese gamosa, the mekhela sador and many hand-woven designs are world-famous.

Mineral-based industries: Assam's four oil refineries at Digboi, Guwahati, Bongaigaon and Numaligarh refine petroleum; the BCPL unit at Lepetkata makes plastic products from natural gas; the Namrup factory makes chemical fertilizers; and the cement factories at Bokajan and Umrangso use the local limestone. There are also small chemical, glass and engineering units.

Cottage and handicraft industries: Assam is famous for its cottage industries. Important among them are: brass and bell-metal work at Sarthebari (Barpeta district), cane and bamboo crafts at several centres, pottery, jewellery, mask-making of the satras (the famous masks of Samaguri Satra), wood-carving and the weaving of muga, eri and pat silk. These crafts give employment to lakhs of village families, especially women.

Industrial development: The government has set up industrial estates and growth centres around Guwahati, Chandrapur, Amingaon and other towns, and has attracted investment through the 'Advantage Assam' programme. Under the Act East Policy, Assam is being developed as a gateway to the markets of South-East Asia. The main problems of Assamese industry are the lack of cheap power and capital, the small size of the local market and the great distance from the big cities of India. Still, tourism, tea, oil, natural gas, silk and the service sector are growing fast and promise a bright future.

Key points to remember:

• Tea processing and petroleum refining are the two largest industries of Assam.
• Assam has about 800 large tea estates.
• The Nagaon Paper Mill is at Jagiroad and the Cachar Paper Mill at Panchgram.
• Assam is the only large producer of golden muga silk in the world.
• Sualkuchi, near Guwahati, is the famous silk-weaving village of Assam.
• Sarthebari is famous for brass and bell-metal work.
• Samaguri Satra is famous for its masks.
• Assam has four refineries, a gas cracker (BCPL), a fertilizer plant at Namrup and cement plants at Bokajan and Umrangso.
• Cottage industries employ lakhs of village families, especially women.
• The Act East Policy makes Assam the gateway to South-East Asia.

According to the Census of India 2011, the population of Assam was 3,12,05,576 (about 3.12 crore). Assam's population is one of the fastest-growing in India. The decadal growth rate between 2001 and 2011 was 16.93 per cent, which is much higher than the national average and the highest among the north-eastern states. The density of population is 397 persons per square kilometre, higher than the national figure of 382.

Composition of the population: The sex ratio of Assam is 958 (females per thousand males), and the child sex ratio (0–6 years) is 962. The literacy rate of Assam is 72.19 per cent (male 77.85 per cent and female 66.27 per cent), which is lower than the all-India rate. Assam is still largely a rural state — only about 14 per cent of the people live in towns and cities, far less than the national average. Agriculture gives employment to the largest part of the working population.

Religion, language and society: The major religions of Assam are Hinduism and Islam, with small but important Christian, Sikh, Buddhist and Jain communities. The Assamese language is the official language of the state. Bodo is used as an associate official language in the Bodo Territorial Region, and Bengali is used as an official language in the three districts of the Barak valley (Cachar, Karimganj and Hailakandi). The Assamese-speaking people live mainly in the Brahmaputra valley, while the Barak valley is predominantly Bengali-speaking. Assam is also the home of many tribal peoples — the Bodo, Mising (Miri), Rabha, Karbi, Dimasa, Tiwa (Lalung), Deuri and Sonowal Kachari among others — each with its own language and culture.

Distribution of population: The population of Assam is very unevenly distributed. The plains of the Brahmaputra valley and the Barak valley are densely populated, while the hill districts of Karbi Anglong and Dima Hasao are thinly populated. Among the districts, Nagaon has the largest population, and the newly formed Majuli district has the smallest. Kamrup Metropolitan (Guwahati) has the highest density of population. Guwahati is the largest city and the chief urban centre; the other important towns are Silchar, Dibrugarh, Jorhat, Tezpur, Nagaon and Bongaigaon.

Population problems and the future: The rapid growth of population, helped by immigration from across the borders, has put heavy pressure on land, forests, housing and public services in Assam. The density of population in the flood-prone river plains is very high, and floods force people to crowd the few safe areas. Urbanisation, though slow, is now increasing, and towns such as Guwahati are growing fast. The next Census of India (which was due in 2021 but was postponed) will give the latest figures. For all competitive exams, the 2011 figures given above are the ones to remember.

Key points to remember:

• The population of Assam in Census 2011 was 3,12,05,576 (about 3.12 crore).
• The decadal growth (2001–2011) was 16.93%, the highest among the north-eastern states.
• The density of population of Assam is 397 per sq km (India: 382).
• The sex ratio is 958 and the child sex ratio is 962.
• The literacy rate is 72.19% (male 77.85%, female 66.27%).
• Only about 14% of the population of Assam lives in urban areas.
• Assamese is the official language; Bodo and Bengali have official status in certain areas.
• Nagaon is the most populous district and Majuli the least populous.
• Kamrup Metropolitan has the highest density of population.
• Guwahati is the largest city and the chief urban centre of Assam.

Transport is of special importance to Assam because the state is the heart of the landlocked north-east. Nearly every north-eastern state depends on the roads, railways and waterways that pass through Assam. Among the different means of transport, roads carry the largest share of passengers and goods.

Roadways: Assam has a fairly good network of roads. National Highway 27 (the east–west corridor) passes through the state, and many national and state highways radiate from Guwahati towards every neighbouring state — Meghalaya, Nagaland, Manipur, Mizoram, Tripura, Arunachal Pradesh and West Bengal. The main road links of Assam are the Guwahati–Siliguri route (which joins Assam with the rest of India), the Guwahati–Shillong route and the Guwahati–Dimapur route. The state highways connect the district headquarters, and village roads have been greatly improved under schemes such as the Pradhan Mantri Gram Sadak Yojana.

Railways: Assam is served by the North-East Frontier Railway (NFR) zone of Indian Railways, whose headquarters is at Maligaon in Guwahati. The important railway lines are the main line from Guwahati through Nagaon, Lumding, Dimapur and Mariani towards Dibrugarh and Tinsukia, and the Lumding–Silchar line, which connects the Barak valley with the rest of Assam through the hill country. All the important routes have now been converted to broad gauge. The Brahmaputra is crossed by the rail-cum-road bridges at Saraighat (Guwahati), Naranarayan Setu (Jogighopa–Pancharatna) and the Bogibeel bridge, which was opened in 2018 and was the longest rail-cum-road bridge of India at the time of its opening. A new line is also being built to connect Assam with the neighbouring states and with Bangladesh.

Airways: Assam is well connected by air. The Lokpriya Gopinath Bordoloi International Airport at Borjhar, near Guwahati, is the biggest airport of the north-east and connects the state with Delhi, Kolkata and other cities of India and abroad. The other important airports are at Dibrugarh (Mohanbari), Jorhat (Rowriah), Tezpur (Salonibari), Silchar (Kumbhirgram) and North Lakhimpur (Lilabari). These airports are of great help to the hilly and far-flung areas of the state.

Waterways and communication: The Brahmaputra from Sadiya to Dhubri (about 891 km) is National Waterway 2. It is used for carrying goods and passengers and, under an agreement with Bangladesh, cargo is carried through the Bangladesh rivers to Kolkata and Haldia. The river ports of Dhubri, Guwahati, Jorhat and Dibrugarh are the important landing points. In the field of communication, Assam is served by an extensive network of roads and post offices, radio and television, and the mobile telephone and internet networks now reach almost every part of the state.

Key points to remember:

• Roads carry the largest share of passengers and goods in Assam.
• National Highway 27 (east–west corridor) passes through Assam.
• Guwahati is the main road, rail and air hub of the north-east.
• The North-East Frontier Railway (NFR) has its headquarters at Maligaon, Guwahati.
• The Lumding–Silchar line connects the Barak valley with the rest of Assam.
• The Bogibeel bridge (2018) was the longest rail-cum-road bridge of India when opened.
• The Brahmaputra is crossed at Saraighat, Naranarayan Setu and Bogibeel.
• The Lokpriya Gopinath Bordoloi International Airport is at Borjhar, Guwahati.
• Other airports: Dibrugarh, Jorhat, Tezpur, Silchar and North Lakhimpur.
• The Sadiya–Dhubri stretch of the Brahmaputra is National Waterway 2.
• Cargo moves to Kolkata and Haldia through Bangladesh under an agreement.

Assam is one of the most disaster-prone states of India. Its special position — surrounded by high mountains, drained by the largest rivers of the region and situated in the highest earthquake-risk zone of the country — makes it liable to floods, river erosion and earthquakes, besides landslides, droughts and severe storms. Of all these, floods and erosion cause loss and suffering to the people every single year.

Floods: Floods are almost an annual feature of the Brahmaputra and Barak valleys. The causes are the very heavy monsoon rain over the whole catchment, the sudden rise of the north-bank rivers coming down from the Himalayan and Arunachal hills, the silting of the river-beds which makes the rivers shallower, and the many breaches of the embankments. Because the Brahmaputra is braided and constantly shifting, it spreads its waters over vast areas. Roughly 40 per cent of the area of Assam is estimated to be flood-prone. The floods drown crops, destroy houses and roads, wash away villages and force lakhs of people to live on embankments and high grounds every year. In some years, floods are followed by drought, which ruins the farmers completely.

River erosion: More dangerous in the long run than the floods themselves is the erosion caused by the shifting rivers, above all the Brahmaputra. Every year the river eats away large stretches of its banks, swallowing villages, cultivable land and even towns. The island district of Majuli, the largest river island in the world, has lost more than half of its original area to erosion since the middle of the twentieth century. Crores of rupees are spent every year on embankments, spurs and bank-protection works, yet the problem remains. The Brahmaputra Board, set up by the Government of India, and the Water Resources Department of the state work on flood control and erosion protection.

Earthquakes: Assam lies in seismic zone V, the zone of the highest earthquake risk in India. This is because the Indian plate is pushing against the Eurasian plate beneath the Himalayas and the north-east. Assam has experienced some of the greatest earthquakes of the world: the great earthquake of 1897, which destroyed Shillong, and the even greater earthquake of 1950 in the Assam–Tibet border region, one of the most powerful earthquakes ever recorded anywhere in the world. The 1950 earthquake changed the course of many rivers and raised or lowered the ground over wide areas. After such an earthquake, the risk of landslides and of floods from dammed rivers becomes very high.

Other natural hazards: The hill districts of Dima Hasao and Karbi Anglong suffer from landslides during heavy rain, made worse by jhum cultivation, road cutting and deforestation. Hailstorms and the strong pre-monsoon storms (Bordoisila) damage standing crops, and in some years weak monsoons bring drought. Climate change is making rainfall more erratic and the floods more severe.

Disaster management: To face these dangers, Assam has set up the Assam State Disaster Management Authority (ASDMA). The Central Water Commission issues flood forecasts, and the state maintains embankments, warning systems and relief arrangements. People are being encouraged to build raised houses and to grow flood-tolerant crops. For competitive exams remember that Assam is in seismic zone V, that floods and erosion are annual problems of the Brahmaputra valley, and that the great earthquakes of Assam occurred in 1897 and 1950.

Key points to remember:

• Assam is one of the most disaster-prone states of India.
• Roughly 40% of the area of Assam is estimated to be flood-prone.
• The Brahmaputra and its tributaries cause floods almost every year.
• River erosion, especially by the Brahmaputra, destroys banks, villages and farmland.
• Majuli has lost more than half of its area to erosion since the mid-twentieth century.
• Assam lies in seismic zone V, the highest earthquake-risk zone of India.
• The two great earthquakes of Assam occurred in 1897 and 1950.
• The 1950 earthquake was one of the most powerful ever recorded in the world.
• Landslides are common in the hill districts of Dima Hasao and Karbi Anglong.
• The Brahmaputra Board works on flood control and erosion protection in Assam.
• The Assam State Disaster Management Authority (ASDMA) coordinates disaster management.