Tribal groups migrated from Tibet during the pre-historic period is considered as the first inhabits of this region. Thai-Burmese tribal groups joined them later.

Except for the northwestern parts of the state, little is known about the history of Arunachal Pradesh, although the Apatani tribe had legendary knowledge of the history. Recorded history was only available in the Ahom chronicles during the 16th century. Tribal groups namely Monpa and Sherdukpen are keeping historical records of existence of local chiefdoms in the northwest. Northwestern parts of this area were ruled by kings of Monpa kingdom of Monyul between 500 B.C. and 600 A.D. This region then came under the loose control of Tibet, especially in the Northern areas. Ahom and the Assamese controlled the remaining parts of the state until the annexation of India by the British in 1858.