The People of Assam inhabit a multi-ethnic, multi-linguistic and multi-religious society. They speak languages that belong to four main language groups: Tibeto-Burman, Indo-Aryan, Tai-Kadai, and Austroasiatic. The large number of ethnic and linguistic groups, the population composition, and the peopling process in the state has led to it being called an "India in miniature".[2]
The peopling of Assam was understood in terms of racial types based on physical features, types that were drawn by colonial administrator Risley. These classifications are now considered to have little validity, and they yield inconsistent results; the current understanding is based on ethnolinguistic groups[3] and in consonance with genetic studies.
Geographically Assam, in the middle of Northeast India, contains fertile river valleys surrounded and interspersed by mountains and hills. It is accessible from Tibet in the north (via Bum La, Se La, Tunga), across the Patkai in the Southeast (via Diphu, Kumjawng, Hpungan, Chaukam, Pangsau, More-Tamu) and from Burma across the Arakan Yoma (via An, Taungup). These passes have been gateways for migration routes from Tibet, Southeastern China and Myanmar. In the west both the Brahmaputra valley and the Barak valley open widely to the Gangetic plains.[4] Assam has been populated via all these accessible points in the past. It has been estimated that there were eleven major waves and streams of ethnolinguistic migrations across these points over time.[5] In recent years, a multidisciplinary approach using archaeological, historical linguistic and genetic data has been used to reconstruct population history.[6]
There is no evidence in Assam and Northeast India of early hominid dispersal.[7] The presence of a Paleolithic culture is contested.[8] An early report of the presence of Dravidian is also not supported.[9] The earliest culture in Assam is Neolithic; there is no evidence of Chalcolithic culture either in the Brahmaputra valley or in the surrounding hills;[10] and state formation began only from middle of 1st millennium CE.[11]
The archaeological sites of Sarutaru in Kamrup and Daojali Hading in Dima Hasao district display neolithic cultures.[17] Some other Neolithic sites in Northeast include those in Arunachal Pradesh, Sadiya, Dibrugarh, Lakhimpur, Nagaon, Naga Hills, Karbi Anglong, Kamrup, Garo and Khasi hills of Meghalaya, etc. The neolithic culture discovered in Assam has East and Southeast Asian affinities of the Hoabinhian tradition.[18]
It had been suggested by linguists and ethnologists more than a hundred years ago that Austroasiatic speakers preceded Tibeto-Burman speakers[19]—and the latest findings from genetic and linguistic studies support the early claim and suggest mechanisms how a section of the Austroasiatic speakers had shifted to Tibeto-Burman.[20]
The earliest inhabitants of Assam are estimated to be late neolithic Austroasiatic peoples who came from Southeast Asia.[21] Genetic studies on O2a1‐M95 Y-chromosomal haplogroup, which has been associated with Austroasiatic speakers in India,[13] show that the expansion of this haplogroup in northeast India occurred more than five thousand years ago.[14] Some linguistic models indicate that the Austroasiatic peoples likely reached the region bringing with it an aquatic culture.[22][23] Historians too have noted that dry rice cultivation reached Assam from Southeast Asia.[24] Though some authors have suggested that the Brahmaputra valley may have been a center of dispersal of the Austroasiatic languages,[25] this has been refuted by others.[26]
They are expected to have settled in the foothills bordering the Brahmaputra valley, to be either absorbed or pushed to the hills by subsequent migrants.[27] The Austroasiatic remnant today are represented by the Khasi and Pnar peoples in neighbouring Meghalaya; and who are also present in Assam's Karbi Anglong and Dima Hasao districts that adjoin Meghalaya,[28][29] and who have traditions placing them in the Brahmaputra valley.[30] It is significant that in the context of the discontinuity in mtDNA in south asian and southeast asian populations the Khasi people have an equal admixture (40% S Asian and 39% SE Asian) of south/east asian mtDNA as opposed to the Munda peoples (the Austroasiatic speakers in eastern India) who have predominantly south Asian mtDNA (75% S Asian and 0% SE Asian).[31]
Jaquesson (2017) suggests that the Garo, Rabha, and some Koch peoples carry linguistic and social traces of past Austroasiatic peoples.[32][33]
The second group of people to reach Assam are considered to be speakers of Tibeto-Burman languages.[34][35] The first Tibeto-Burman speakers started coming into Assam some time before three thousand years ago from the north and the east.[15][36] And they have continued coming into Assam till the present times.[34] It is indicated that this population could be associated with the O-M134 y-chromosome haplogroup.[37] There is widespread agreement among linguists and ethnographers that the Tibeto-Burmans migrated into an already settled region,[38][19][35] which is consistent with genetics studies.[39] They are today represented by the Bodo-Kacharis, the Karbi and the Mising; the Monpas and Sherdukpens; and Naga peoples.[40] Over time, two distinct Tibeto-Burman linguistic regions emerged in northeast India—(1) highlands surrounding the Brahmaputra valley that is predominantly Tibeto-Burman with great diversity,[41] and (2) plains where there are fewer but fairly homogenised Tibeto-Burman languages spread over a much larger area and in contact with Indo-Aryan and other language families.[42]
DeLancey (2012) suggests that the Boro-Garo languages, the most widespread group of Tibeto-Burman languages in the plains, have a comparatively transparent grammar and an innovative morphology[43] which indicates that proto-Boro-Garo must have emerged from a creolised lingua franca which is comparable to the case of Nagamese,[44] during a time when it was being used by non-native speakers.[45][46] A section of these Tibeto-Burman speakers could have been native Austroasiatic speakers, as suggested by some genetic studies on present-day Tibeto-Burman peoples of northeast India.[47] It is expected that the Tibeto-Burman peoples were not as numerous as the indigenous Austroasiatic population, and the replacement was of languages and not peoples.[48] The arrival of the Indo-Aryans and the expansion of the Kamarupa kingdom over the entire Brahmaputra valley created the conditions for the creolisation and development of proto-Boro-Garo lingua franca.[49]
Medieval historical sources suggest that the Bodo-Kacharis were adept at gravitational irrigation,[50] and though they were immersed in ahu rice culture some of them raised a wet rice called kharma ahu that was irrigated but not necessarily transplanted.[51] These irrigation systems continued to be used by Austroasiatic and Tibeto-Burman groups in modern times.[52] In this context, it is significant that most river names in Assam such as Dibang, Dihang, Doyang, start with Di-, (water in Tibeto-Burman)[53] and end in -ong (water in Austric languages).[54]
Eye witness accounts of the Austroasiatic and Tibeto-Burman peoples come from the Periplus of the Erythraean Sea (1st century CE) and Ptolemy's Geography (2nd century CE) that call the land Kirrhadia after the Indo-Aryan name for the non-Indo-Aryan Kirata people who were the source of Malabathrum, so priced in the classical world.[55]
The Indo-Aryan migration to Assam that began in the first millennium BCE is the third stream.[56] Based on paleographic evidence Indo-Aryans spread into Assam early[57] but it cannot be pushed beyond the 5th century BCE.[16] The early Indo-Aryans were cultivators who brought with them the technology of wet rice (sali) cultivation, the plough, and cattle.[58] The earliest direct epigraphic evidence of Indo-Aryans in Assam comes from the 5th-century CE Umachal[59] and Nagajari-Khanikargaon rock inscriptions, written in the Indo-Aryan Sanskrit language.[60] When Indo-Aryan speakers entered the Brahmaputra valley, Austroasiatic languages had not yet been entirely replaced by the Tibeto-Burman languages, since an Austroasiatic substratum in the later-day Assamese language that emerged from the earlier Indo-Aryan vernacular indicates that Austroasiatic languages were present at least till the 4th- and 5th centuries CE.[61]
The presence of Indo-Aryans in the Brahmaputra valley triggered its historical period with the establishment of the Kamarupa kingdom.[62] The kings of this kingdom were originally non-Indo-Aryan who were sanskritised,[63] and who encouraged immigration and settlements of Indo-Aryans as landlords of already settled cultivators. The land grants were written in Sanskrit, but the presence of Austroasiatic, Tibeto-Burman and vernacular Indo-Aryan words and formations in these grants indi