The Dooars or Duars (/duˈɑːrz/) are the alluvial floodplains in eastern-northeastern India and southern Bhutan that lie south of the outer foothills of the Himalayas and north of the Brahmaputra River basin. This region is about 30 km (19 mi) wide and stretches over about 350 km (220 mi) from the Teesta River in West Bengal to the Dhansiri River in Udalguri district of Assam. The region forms the gateway to Bhutan. It is part of the Terai-Duar savanna and grasslands ecoregion.

Dooars means 'doors' in Assamese, Kamtapuri, Bengali, Maithili, Bhojpuri, and Magahi languages. There are 18 passages or gateways between the hills in Bhutan and the plains in India. This region is divided by the Sankosh River into Eastern and Western Dooars, consisting of an area of 880 km² (340 sq mi).

The Dooars belonged to the Kamata Kingdom under the Koch dynasty; They acted as a trade route between Assam and Bhutan. Assam exports wäre muga, silk cloth, endi cloth, dried fish and rice and imports consisted of woollen cloth, gold-dust, rock salt, yaktails musk, ponies and blankets from Bhutan.

In the early 17th century, the combined forces of Ahoms and Koches temporarily checked the Bhutia's transgression. During this period two important Duars on the Darrang frontier, Buriguma and Killing were under Ahoms control. During the Ahom–Mughal conflicts in the mid-17th century, the Bhutias attempted to extend their authority as far as Gohain Kamal Ali road.

In the reign of Ahom king Jayadhwaj Singha, the Druk Desi of Bhutan requested the transfer of these Duars to Bhutan. Therefore, an agreement was drawn, and the Darrang Duars went to the hands of Bhutias on the condition of annual tribute to the Ahoms. The Darrang Duars were also surrendered to Ahoms annually for four months from June to October. These Duars were properties of Ahom government, but the Druk Desi of Bhutan took possession of them in last phase of 18th century when the Ahoms were engaged in internal rebellions.

This region was controlled by the kingdom of Bhutan when British India annexed it in 1865 after the Duar War under the command of Captain Hedayat Ali. Bhutan lost almost one-fifth of its area in this war.

The area was divided into two parts: Western Dooars and Eastern Dooars. The Western Dooars were under the Kingdom of Cooch Behar State from 1586 to 1949, and the Eastern Dooars under the Kingdom of Koch Hajo. Under the Koch government, the officer-in-charge of the Duars were called Subahdar. Similar office existed under the Bhutan government, the Subah was selected by the provincial governors called Ponlops. The Ahom government managed the Duars through Duarieas. The other two Dooars were the Kamrup Duars and Darrang Duars. The Eastern Dooars was merged with Goalpara district in Assam, the Kamrup Dooars was merged with Kamrup district, the Darrang Dooars was merged with Darrang District and the western part was turned into a new district named Western Dooars. Again in the year 1869, the name was changed to Jalpaiguri district.

The Western Dooars are part of the Duars of northern part of West Bengal, India or those located to the west of Goalpara district of Assam. The Western Dooars came under the British in 1865.The region comes under the Kalimpong district, Jalpaiguri district, Alipurduar district and some parts of Cooch Behar district. The Western Dooars were created in 1865. It was merged with the Jalpaiguri district in 1869.^{[citation needed]}