In this political vacuum Biswa Singha managed to unify different tribal groups and establish the Koch dynasty in the seat of the erstwhile Kamata kingdom.
Bisu, as he was then known, was born to Hariya Mandal of Mount Chikna in present-day Kokrajhar district of Assam, the head of twelve Mech families[3] and Hira, the daughter of Hajo, a Koch leader[4] in the later part of the 15th century.
[14] Brahman priest created a legend of Bisu being born as the son of Shiva to give legitimacy to his rule[15] and bestowed on him the status of kshatriya varna and here he took the Hindu name Biswa Singha.
[20] In order to maintain a tribe-centric policy, Biswa Singha instructed his ministers not to get brides from foreign people but instead from the Koch, Mech or Kachari tribes.
Malladev (later Nara Narayana was the heir apparent; Sukladhwaj (later Chilarai), Gosain Kamal (son of Chandrakanti of Kamarupa) was in charge of public works.
[22] In Yogini Tantra, a 16th/17th century text describes Biswa Singha as the conqueror of Kàma(rupa) (Kamrup), Saumàra (Ahom) and Gaudapañcama (Gauda).
[25] Turbak was summarily defeated, and the remnant of his army was pursued to the Karatoya river, the western boundary of the Kamata kingdom, by the Ahom general Tonkham Borgohain.
During his reign Muslim invaders, including Turuk Khan and Nasrat Shah, the king of Gour attacked his kingdom numerous times but after facing defeat they were forced to retreat.
He sent his two son Nara Narayan & Sukladhaj (Chilarai) to a Sanskrit scholar named Brahmananda in Varanasi to introduce them to the ideals of higher caste Hindus.
[27] He later brought several priests from places like Kanauj, Mithila, Benaras and Puri (Srikshetra) to perform Brahminical rites that led to the sankristisation of the Koch royal family from tribalism.