In British India, the major part of the hills came under the Naga Hills district. apart of Naga Hills under the British India controlled was coalesced into a district in 1866. the boundaries of Naga Hills district were gradually expanded by annexation of the territories of several Naga ethnic groups including the Aos, the Semas and the konyaks. In 1912 the district was made part of Assam province following the partition of India, it was merged with Tuensang Divvision to create the state called Nagaland in 1963.