Northeast India is the eastern-most region of India connected to East India via a narrow corridor squeezed between Nepal and Bangladesh. It comprises the contiguous Seven Sister States (Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, and Tripura), plus the Himalayan state of Sikkim. These states are grouped under the MDONER ministry of the Government of India. Except for the Goalpara region of Assam, the rest were late entrants to the British India, the Brahmaputra valley area of Assam became a part of British India in 1824, and the hill regions were incorporated even later.
Sikkim joined the Indian union through a referendum in 1975 and was recognised as part of Northeast India in the 1990s.
In terms of geographical size, Northeast India constitute about 8% of the total India's size, and is roughly 3/4th the size of the state of Maharashtra. Northeast India's population (all 8 states combined) is approximately 40 million (2011 census), which represents 3.1% of the total Indian population (1,210 million). Northeast India's population size is roughly equal to the state of Odisha.
The Siliguri Corridor in West Bengal, with a width of 21 to 40 kilometres (13 to 25 mi),connects the North Eastern region with the main part of India. The region shares more than 4,500 kilometres (2,800 mi) of international border (about 90 per cent of its entire border area) with China (South Tibet) in the north, Myanmar in the east, Bangladesh in the southwest, and Bhutan to the northwest.
The states are officially recognised under the North Eastern Council (NEC), constituted in 1971 as the acting agency for the development of the eight states. The North Eastern Development Finance Corporation Ltd (NEDFi) was incorporated on 9 August 1995 and the Ministry of Development of North Eastern Region (DoNER) was set up in September 2001.