present-day Kokrajhar district, though these ethnic identities are difficult to discern since there were frequent intermarriages. Bisu, born to Hariya and Hira, acquired the political legacy of his grandfather Hajo and established himself as the chief of the eastern branch of the Koches in the Khuntaghat region (present-day Kokrajhar district of Assam). It is thought that Bisu fought under the leadership of the Bhuyans as a landlord against the occupation of Kamata kingdom by Alauddin Husain Shah and thus learned their military tactics. Consolidation of power under Bisu He sought the alliance of tribal chiefs, against the more powerful Baro-Bhuyans and began his campaign around 1509. Successively, he defeated the Bhuyans of Ouguri, Jhargaon, Karnapur, Phulaguri, Bijni and Pandunath (Pandu, in Guwahati). He was particularly stretched by the Bhuyan of Karnapur, and could defeat him only by a stratagem during Bihu. In some records Bisu moved his capital from Chikana to Hingulabas (near present-day Samuktala) and then finally to Kamatapur (now called Gosanimari) which is just a few miles southeast of the present-day Cooch Behar town—but since these movements were recorded much after the events the dates and rulers associated with these movements are not expected to be accurate and these movements represent the gradual movement of Koch power towards the southern plains of the Brahmaputra valley. After subjugating the petty rulers, he announced himself the king of Kamata bounded on the east by Barnadi river and on the west by the Karatoya river in the year 1515. The Koch dynasty in Kamata was one of several tribal formations that developed into statehoods around 15th century in northeast India—Ahom, Chutia, Dimasa, Tripura, Manipur, etc. Sanskritisation At his coronation Bisu adopted Hinduism and the name Biswa Singha. Nevertheless, he retained the Koch identity of his mother discarding the ethnic identity of his father. Later, Brahman pundits created a legend that lord Siva was the father of Biswa Singha to give legitimacy to his rule and conferred on him the status of the Kshatriya varna. According to the legend constructed at the time of coronation, Bisu was son of Siva and his tribe either the Koch or Mech people were Kshatriyas who ran away from the fear of extermination by the Brahman sage Parashurama and took shelter in Western Assam and Northern Bengal and later disguised themselves as Mlechchas. This process of hinduisation was much slower in the lower strata of the