Northeast India is a politically vital and strategically vulnerable region of India. Surrounded by five countries, it is connected with the rest of India through a narrow, thirty-kilometre corridor. North- East India, then called Assam, is divided into Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland and Tripura. Diversities in terms of Mongoloid ethnic origins, linguistic variation and religious pluralism characterise the region. This ethnic-linguistic-ecological historical heritage characterizes the pervasiveness of the ethnic populations and Tibeto-Burman languages in northeast. North-East mountain ranges and river valleys indeed divide up South- East Asia from South Asia. This predominant tribal region, replete with protracted records of isolation, difficult terrain, and lack of intense inter-ethnic contacts, had witnessed formation of three types of society and polity such as 'tribe', 'chiefdom' and 'state' (Das 1989). The clans and age set systems within them had often functioned hierarchically involving unequal statuses (Das 1993). Full-fledged stateformation took place in the 4th century A.D.. Hinduism remained confined to some pockets, including the royal families, among the Kachari, Ahom, Jaintia, Koch, Tripuri, and Meitei. Penetration of Sarania dharma of Shankar Dev was felt in some plains tribal societies, who became followers of Sarania even while simultaneously pursuing tribal religions often replete with animal sacrifices' (Das 2003).