Eastern South Asia region is bounded by Nepal, Sikkim, and Bhutan in the north, Bangladesh in the east, the Indian states of Uttar Pradesh and Chhattisgarh on the west, and the Indian state of Andhra Pradesh in the south. It is connected to the Seven Sister States of Northeast India by the narrow Siliguri Corridor. West Bengal is on the eastern bottleneck of India, stretching from the Himalayas in the north, to the Bay of Bengal in the south. The region lies in the humid-subtropical zone. The landlocked region of Northeast India includes the states of Assam, Arunachal Pradesh, Bihar, Mizoram, Manipur, Meghalaya,
Sino-Indian border dispute the Himalayas and the areas south of the Himalayas were traditionally Indian and associated with India. The high watershed of the Himalayas was proposed as the border between India and its northern neighbours. India's government held the view that the Himalayas were the ancient boundaries of the Indian subcontinent and thus should be the modern boundaries of British India and later the Republic of India. Chinese boundary markers, including one set up by the newly created Chinese Republic, stood near Walong until January 1914, when T. O'Callaghan, an assistant administrator of North East Frontier Agency (NEFA)'s eastern sector, relocated them