Racially the Karbis belong to the Mongoloid group and linguistically they belong to the Tibeto-Burman group. The original home of the various people speaking Tibeto-Burman languages was in western China near the Yang-Tee-Kiang and the Howang-ho rivers and from these places they went down the courses of the Brahmaputra, the Chindwin and the Irrawaddy and entered India and Burma. The Kabis, alongwith others entered Assam from Central Asia in one of the waves of migration.But, it is very difficult to trace the history of the early settlement of the Karbis bereft of any written documents and other evidence like archaeological remains, etc. Of course, in the old chronicles and Buranjis occasional references here and there were made to the people of this race. But from these references also it is very difficult to trace the chronological events of the Karbis. Their folk-tales and folk-lores are the only sources from which it can have an idea regarding their early history.

Excerpt from http://karbianglong.gov.in/main-web/tribes-culture.htm