Explanation:

In 1963, Nagaland was formed when Naga Hills district became the 16th state of India.

Since 1970, Government of India has divided Assam into various states as Government of India has the unilateral power to change the borders of the state. Assam was divided into various states in order to satisfy national aspirations of the tribal populations living within the then borders of then Assam.

• In 1963, Nagaland was formed when Naga Hills district became the 16th state of India. Tuensang part was added to Nagaland.