Assam is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of 78,438 km2, The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur to the east; Meghalaya, Tripura, Mizoram and Bangladesh to the south; and West Bengal to the west via the Siliguri Corridor, a 22 kilometres wide strip of land that connects the state to the rest of India.
Assam is one of the richest biodiversity zones in the world and consists of tropical rainforests, deciduous forests, riverine grasslands, bamboo orchards and numerous wetland ecosystems; Many are now protected as national parks and reserved forests.
Assam has wildlife sanctuaries, the most prominent of which are two UNESCO World Heritage sites-the Kaziranga National Park, on the bank of the Brahmaputra River, and the Manas Wildlife Sanctuary, near the border with Bhutan. The Kaziranga is a refuge for the fast-disappearing Indian one-horned rhinoceros. The state is the last refuge for numerous other endangered and threatened species including the white-winged wood duck or deohanh, Bengal florican, black-breasted parrotbill, red-headed vulture, white-rumped vulture, greater adjutant, Jerdon's babbler, rufous-necked hornbill, Bengal tiger, Asian elephant, pygmy hog, gaur, wild water buffalo, Indian hog deer, hoolock gibbon, golden langur, capped langur, barasingha, Ganges river dolphin, Barca snakehead, Ganges shark, Burmese python, brahminy river turtle, black pond turtle, Asian forest tortoise, and Assam roofed turtle. Threatened species that are extinct in Assam include the gharial, a critically endangered fish-eating crocodilian, and the pink-headed duck, For the state bird, the white-winged wood duck, Assam is a globally important area. In addition to the above, there are three other National Parks in Assam namely Dibru Saikhowa National Park, Nameri National Park and the Orang National Park.
Assam has conserved the one-horned Indian rhinoceros from near extinction, along with the pygmy hog, tiger and numerous species of birds, and it provides one of the last wild habitats for the Asian elephant. Kaziranga and Manas are both World Heritage Sites. The state contains Sal tree forests and forest products, much depleted from earlier times. A land of high rainfall, Assam displays greenery. The Brahmaputra River tributaries and oxbow lakes provide the region with hydro-geomorphic environment.
The state has the largest population of the wild water buffalo in the world.The state has the highest diversity of birds in India with around 820 species. With subspecies the number is as high as 946.The mammal diversity in the state is around 190 species.