Assam is a state in Northeast India, located south of the Eastern Himalayas along the Brahmaputra Valley and Barak River valleys. It covers an area of 78,438 km2 (30,285 sq mi), and is the second largest state in northeastern India by area. As per the 2011 census, the state had a population of 31.2 million, and is the largest by population in the region. It shares international borders with Bhutan to the north and with Bangladesh to the southwest. It borders the Indian states of Arunachal Pradesh to the north; Nagaland and Manipur to the east; Meghalaya, Tripura, and Mizoram to the south; and West Bengal to the west. It is connected to the rest of the India to the west via the Siliguri Corridor(also known as the chicken neck), a 22 km (14 mi) wide strip of land. Dispur is the capital of Assam while Dibrugarh is the second capital. Guwahati is the largest city and urban area in the state.
Archaeological evidence from the region indicate early settlements from the second to first century BCE. Though the region finds mention in the Hindu epic Mahabharata, there is a lack of substantial archaeological evidence regarding its ancient history. The region is described as one of the frontiers of the Gupta Empire in fourth century CE. It was ruled by Varmanas (c. 350–650 CE), Mlechchhas (c.655–900 CE) and Kamarupa-Palas (c. 900–1100 CE) later. The Ahom kingdom was established in the 13th century CE, and ruled till the early 19th century CE. The period saw various conflicts with the Mughals. After the Moamoria rebellion and Burmese invasions weakened the Ahom kingdom, the British started establishing tea estates in the region in the 19th century CE. The region became part of the Bengal Presidency, and the Assam Province was established in 1912. The Assam Legislative Assembly was formed in 1937. The province became part of Independent India on 15 August 1947, and was recognised as a state after India became a republic on 26 January 1950.
The state is organised into 35 districts across five divisions. Assamese and Bodo are the official languages of the state with Meitei recognised as an additional official language in three districts of the Barak Valley and Hojai district, and Bengali in the Barak Valley. The state is known for its namesake Assam silk and Assam tea, recognised as Geographical Indications in India. Oil was discovered in the region in 1867, and oil drilling started in 1889. Wildlife tourism is a major contributor to the economy of the state, aided by the presence of various protected areas including the Kaziranga and Manas National Parks, which are World Heritage Sites. More than half of the extant wild population of the one-horned Indian rhinoceros occurs in the state. The state is a rich biodiversity zone consisting of various ecosystems including tropical rainforests, deciduous forests, riverine grasslands, orchards, and wetlands. It receives copious amount of rainfall, which feeds the Brahmaputra River system, whose tributaries and oxbow lakes form a distinctive hydro-geomorphic environment.
The first dated mention of the region comes from Periplus of the Erythraean Sea (1st century) and Ptolemy's Geographia (2nd century), which calls the region Kirrhadia, apparently after the Kirata population. In the classical period and up to the 12th century, the region east of the Karatoya River, largely congruent to present-day Assam, was called Kamarupa, and alternatively, Pragjyotisha. Though a western portion of Assam as a region continued to be called Kamrup, the Ahom kingdom that emerged in the east, and which came to dominate much of the Brahmaputra Valley, was called Assam (e.g. Mughals used Asham); and the British province too was called Assam. Though the precise etymology of Assam is not clear, the name Assam, first used by the British in the Treaty of Yandabo in 1826, is associated with the Ahom people, originally called Shyam (Shan).
Assam and adjoining regions have evidences of human settlement from the beginning of the Stone Age. The hills at the height of 1,500 to 2,000 feet (460–615 m) were popular habitats probably due to availability of exposed dolerite basalt, useful for tool-making.
Ambari site in Guwahati has revealed Shunga-Kushana era artefacts including flight of stairs and a water tank which may date from 1st century BCE and may be 2,000 years old. Experts speculate that another significant find at Ambari is Roman era Roman roulette pottery from the 2nd century BCE. Gupta explains that while Guwahati, formerly known as Pragjyotishpur in ancient times, is mentioned in epics like the Mahabharata and the Puranas, there is a lack of substantial archaeological evidence regarding its ancient history, especially before the 7th century AD.
According to a late text, Kalika Purana (c. 9th–10th century CE), the earliest ruler of Assam was Mahiranga Danava of the Danava dynasty, which was removed by Narakasura of Mithila and established the Bhauma dynasty. The last of these rulers, also Narakasura, was slain by Krishna. Naraksura's son Bhagadatta became the king, who (it is mentioned in the Mahabharata) fought for the Kauravas in the battle of Kurukshetra with an army of kiratas, chinas and dwellers of the eastern coast. At the same time towards the east in central Assam, Asura kingdom was ruled by another line of kings.
Evidence indicates presence of civilisation in Assam around 2nd century BCE, a rock cut stupa at Sri Surya Pahar has been dated to 200 BCE contemporary with rock cut Karle and Bhaja caves of Maharashtra. The site is located in a hilly terrain where several rock-cut shivalingas, votive stupas and the deities of Hindu, Buddhist and Jain pantheon are scattered. Samudragupta's 4th-century-CE Allahabad pillar inscription mentions Kamarupa and Davaka (Central Assam) as frontier kingdoms of the Gupta Empire. Davaka was later absorbed by Kamarupa, which grew into a large kingdom that spanned from Karatoya River to near present Sadiya and covered the entire Brahmaputra Valley, North Bengal, parts of Bangladesh and, at times Purnea and parts of West Bengal. The kingdom was ruled by three dynasties who traced their lineage from a mleccha or Kirata Naraka; the Varmanas (c. 350–650 CE), the Mlechchha dynasty (c.655–900 CE) and the Kamarupa-Palas (c. 900–1100 CE), from their capitals in present-day Guwahati (Pragjyotishpura), Tezpur (Haruppeswara) and North Gauhati (Durjaya) respectively. All three dynasties claimed descent from Narakasura. In the reign of the Varman king, Bhaskaravarman (c. 600–650 CE), the Chinese traveller Xuanzang visited the region and recorded his travels. Later, after weakening and disintegration (after the Kamarupa-Palas), the Kamarupa tradition was extended to c. 1255 CE by the Lunar I (c. 1120–1185 CE) and Lunar II (c. 1155–1255 CE) dynasties.
The Medieval Assam history may have started with the advent of Ahoms in the early part of the 13th century and covers their entire rule of 600 years till 1826. After the Bengal-Kamata War, the Khen dynasty ended, and Alauddin Hussain Shah issued coins in his name to be "Conqueror of Kamarup and Kamata". The medieval history of Assam is especially known for its conflict with Muslim powers under Turko-Afghan and Mughals, finally resulting in Assamese victory, however, this military glory was shattered in the early 19th century when it failed to resist the Burmese invasions, which led to its annexation.
Chutia, a Bodo-Kachari group by origin, held the regions on both the banks of Brahmaputra with its domain in the area eastwards from Vishwanath (north bank) and Buridihing (south bank), in Upper Assam and in the state of Arunachal Pradesh. It was annexed by the Ahoms in the year 1524. The rivalry between the Chutias and Ahoms for the supremacy of eastern Assam led to a series of conflicts between them from the early 16th century.
The Dimasa, a Bodo-Kachari dynasty that ruled from the 13th century until 1854, controlled territories stretching from the Dikhow River to central and southern Assam, with their capital at Dimapur. By the early 16th century, with the expansion of the Ahom kingdom, the Chutia regions were annexed, and by around 1536, the Kacharis were confined to the areas of Hojai, North Cachar, and parts of Karbi Anglong, later expanding to Cachar. At this point, they became more of an ally to the Ahoms than a rival force.