80. When did the political map of Northeast India undergo a major change, and what new statesunion territories came into being

In 1972, the two union territories of Manipur (19th state) and Tripura (20th state) and the sub-state of Meghalaya (21st state) got statehood. The two union territories of Mizoram and Arunachal Pradesh (originally NEFA) also came into being from Assam territories.