Explanation:

The government of India, which has the unilateral powers to change the borders of a state, divided Assam into several states beginning in 1970 within the borders of what was then Assam. In 1963, the Naga Hills district became the 16th state of India under the name of Nagaland. Part of Tuensang was added to Nagaland. In 1970, in response to the demands of the Khasi, Jaintia and Garo people of the Meghalaya Plateau, the districts containing the Khasi Hills, Jaintia Hills, and Garo Hills were formed into an autonomous state within Assam; in 1972 this became a separate state under the name of Meghalaya. In 1972, Arunachal Pradesh (the North East Frontier Agency) and Mizoram (from the Mizo Hills in the south) were separated from Assam as union territories; both became states in 1986.