The vast, flat, fertile alluvial lowland of northern India formed by the deposition of sediment by the Indus, Ganga, and Brahmaputra river systems between the Himalayas and the Peninsular plateau.
- Built up over millions of years by alluvium deposited by three river systems (Indus, Ganga, Brahmaputra) in the foredeep (a structural trough) in front of the rising Himalayas.
- Extremely level and fertile, one of the most intensively farmed and densely populated regions in the world; the heartland of Indian agriculture and population.
- Divided north to south into relief belts: bhabar (porous gravel piedmont where streams sink), terai (marshy, re-emerged water belt), bhangar (older alluvium with kankar), and khadar (newer flood-plain alluvium).
- Provides easy transport, large groundwater reserves, and rich farmland; it supports wheat, rice, and sugarcane and a huge population.
- Stretches across Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, West Bengal, and the Brahmaputra valley of Assam.
The three-river origin, the bhabar-terai-bhangar-khadar belts, the fertility and dense population, and the spread across northern States are recurring physiography and agriculture facts.
The relief belts run in order from the hills outward: bhabar (gravelly, streams disappear), terai (marshy, streams re-emerge), then bhangar (older) and khadar (newer) alluvium. The plain is depositional, formed by rivers, not by folding or faulting.
Flat fertile alluvial plain of the Indus-Ganga-Brahmaputra; relief belts bhabar, terai, bhangar, khadar; India's agricultural and population heartland.