I (c.1120-1185 AD) and Lunar II (c.1155-1255 AD) dynasties. [16] Two later dynasties, the Ahoms and the Koch left larger impacts. The Ahoms, originally a Tai group, ruled Assam for nearly 600 years (1228–1826) and the Koch , a Tibeto-Burmese , established sovereignty in c.1510 AD. The Koch kingdom in western