Assam, state of India. It is located in the northeastern part of the country and is bounded to the north by the kingdom of Bhutan and the state of Arunachal Pradesh, to the east by the states of Nagaland and Manipur, to the south by the states of Mizoram and Tripura, and to the west by Bangladesh and the states of Meghalaya and West Bengal. The name Assam is derived from the word asama, meaning “peerless” in the now extinct Ahom language. The neighbouring states of Arunachal Pradesh, Nagaland, Mizoram, and Meghalaya were once part of Assam. The capital, formerly Shillong (now the capital of Meghalaya), was shifted to Dispur, a suburb of Guwahati, in 1972. Area 30,285 square miles (78,438 square km). Pop. (2011) 31,169,272.
Relief and drainage
Assam, which is shaped roughly like a Y laid on its side, is a land of plains and river valleys. The state has three principal physical regions: the Brahmaputra River valley in the north, the Barak River (upper Surma River) valley in the south, and the hilly region between Meghalaya (to the west) and Nagaland and Manipur (to the east) in the south-central part of the state. Of those regions, the Brahmaputra River valley is the largest. According to Hindu mythology, the Brahmaputra rises as the son of the god Brahma from a sacred pool known as the Brahmakund, in neighbouring Arunachal Pradesh. The river enters Assam near Sadiya in the extreme northeast and runs westward through the length of Assam for nearly 450 miles (725 km) before turning south to enter the plains of Bangladesh.
Studded with low, isolated hills and ridges that rise abruptly from the plain, the valley is rarely more than 50 miles (80 km) wide and is surrounded on all sides, except on the west, by mountains. Numerous streams and rivulets that flow from the neighbouring hills empty into the Brahmaputra. Although only a small portion of the Barak River valley lies within Assam’s borders, it nevertheless forms an extensive lowland area that is important for agriculture in the state’s southern region. Geologically, the Brahmaputra and Barak valleys lie on ancient alluvial sediments, which themselves cover a variety of deposits from the Neogene and Paleogene periods (i.e., some 2.6 to 65 million years old). Among those deposits are hard sandstone, soft and loose sand, conglomerates, coal seams, shales, sandy clays, and limestone.