doab

Doab is a geographic term for a tract of land lying between two confluent rivers. The name derives from Persian do (two) and ab (water). In the Indian subcontinent, doabs are common where river systems create broad, depositional plains with fertile alluvial soils. These regions have historically supported large-scale agriculture and the growth of settlements along the river corridors.

Geographically, a doab is defined by the space between the courses of two rivers after they meet or before they join a larger river. The boundaries are not fixed and may shift with seasonal changes in river channels and floodplains. The most well-known doabs include the Ganga–Yamuna Doab in northern India (the land between the Ganges and Yamuna in Uttar Pradesh and neighbouring regions); the Beas–Sutlej, Ravi–Beas, and Chenab–Jhelum doabs in the Punjab areas of India and Pakistan.

The doabs are characterized by rich alluvium, extensive irrigation, and high agricultural productivity, supporting crops like wheat, rice, and sugarcane. They have also served as major routes for trade and cultural exchange, contributing to urban growth along river towns. Today, the term remains a geographic concept rather than an administrative designation, used to describe landscapes formed by the interaction of paired river systems.