In 1826, the British exercised their control in Assam after the treaty of Yandaboo concluded on 24th February 1826. Before 1962, Arunachal was popularly called North Eastern Frontier Agency and was constitutionally a part of Assam. It was administered by the Ministry of External Affairs until 1965 and subsequently by the Ministry of Home Affairs through the Governor of Assam. 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.