During the pre-colonial period, Assam was ruled by the Ahoms. The kingdom of Assam was bounded on the north, east and south by hills inhabited by various tribes, each with distinctive manners, customs and languages. With the advent of the Ahom kingdom in the first half of the thirteenth century, the political scenario of the entire Brahmaputra valley underwent a significant transformation. The maintenance of peace and tranquillity in the country and its protection from foreign attacks constitute the common objective of every government. But the Ahom rulers of Assam were confronted with the additional responsibility of protecting the subjects from the inroads of the tribes inhabiting the hills on the immediate borders.
Dopu Doke (Thu,) studied this question.