The aboriginals of Arunachal Pradesh migrated from Tibet. There are practically no records relating to the earlier history of this place except some oral literature and the number of historical ruins found mainly in the foot hills dating from the early Christian Era. Earlier Arunachal was popularly called North Eastern Frontier Agency and was constitutionally a part of Assam. Until 1965, the Ministry of External Affairs administered it and later by the Ministry of Home Affairs through the Governor of Assam. The tribe consisted of the Daflas, Bangnis, Monpas and they were influenced by Buddhist ideals. In the 16th century the Ahom kings influenced the region. The population were of Tibeto-Burmese linguistic origin. The tribe consisted of the Daflas, Bangnis, the Monpas and they were influenced. Besides them the Membas, Ramos and Boris formed minor groups. The Mishmis exists as Idus, Taraons, and Kamans. They excelled in handicrafts. In 1913-14, the British administrator, Sir Henry McMahon, drew up the McMahon Line as the border between British India and Tibet during the Simla Conference, as Britain sought to advance its line of control and establish buffer zones around its colony in South Asia. The Tibetan and British representatives at the conference agreed to the line, however the Chinese representative refused to accept the line owing to domestic pressures. So the line appeared to be invalid without Chinese agreement. Refusing to sign the Simla documents, the Chinese Government escaped according any recognition to the validity of the McMahon Line.
The situation developed when India became independent and the People`s Republic of China was established in the late 1940. India unilaterally declared the McMahon Line to be the boundary in November 1950, and forced the Tibetan administration out of the Tawang area in 1951. The issue erupted again during the Sino-Indian War of 1962. During the war in 1962 China was victorious and voluntarily withdrew back to the McMahon Line and returned Indian prisoners of war in 1963. The war has resulted in the termination of barter trade with Tibet.
Until 1972, Arunachal Pradesh was administered as the North East Frontier Agency (NEFA). In 1972, it was constituted as a Union Territory and renamed Arunachal Pradesh. On 20th February in 1987, it became the 24th state of the Indian Union.