The Dooars or Duars are the floodplains and foothills of the eastern Himalayas in North-East India around Bhutan. Duar means door in Nepali Bhojpuri, Magahi, and Bengali languages, and the region forms the gateway to Bhutan from India. There were 18 passages or gateways through which the Bhutanese people can communicate with the people living in the plains. This region is divided by the Sankosh river into the eastern and the western Duars, consisting of an area of 8,800 square kilometers (3,400 square-miles). The Western Dooars is known as the Bengal Dooars and the Eastern Dooars as the Assam Dooars. Dooars is synonymous with the term Terai used in Nepal and northern India.

Innumerable streams and rivers flow through these fertile plains from the mountains of Bhutan. In Assam, the major rivers are the Brahmaputra and Manas, and in northern West Bengal the major river is the Teesta besides many others like the Jaldhaka, Torsha, Sankosh, Dyna, Karatoya, Raidak, and Kaljani rivers, among others.

The beauty of the region lies not only in its tea gardens but also in the dense jungles that make up the countryside. Famous wildlife sanctuaries and national park like Manas National Park in Assam; the Jaldapara Wildlife Sanctuary; Buxa National Park; Gorumara National Park; Chapramari Wildlife Reserve; and the Mahananda Wildlife Sanctuary in West Bengal are located in this region.

Number of rare, endangered species of animals like tiger, rhinoceros, elephant, make their habitats in the forests of the Dooars. Other animals includes different types of deer, bison, birds and reptiles.