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,
Ecology of the Himalayas canyons in the world. At the middle elevations of the range, the subtropical forests yield to a belt of temperate broadleaf and mixed forests growing between , with the western Himalayan broadleaf forests to the west of the Gandaki River, and the eastern Himalayan broadleaf forests to the east. The western broadleaf forests stretch from the Kashmir Valley, across Himachal Pradesh and Uttarakhand, and through western Nepal. The eastern broadleaf forests stretch across eastern Nepal, through Sikkim and Bhutan, and through much of Arunachal Pradesh. This 'hilly' region ("Pahad"), averaging about immediately north of the Mahabharat Range, rises to about