Himalayan silt feeds a plain holding one-seventh of humanity
The Indo-Gangetic—or North Indian—Plain spreads about 700,000 square kilometres of fertile silt across northern South Asia from the Himalayas to the Deccan’s edge and from northeast India to near Iran. Nearly one-seventh of the world’s people live on this alluvial stage of empires.
The Indus, Ganges and Brahmaputra dumped sediment into a trough between the rising mountains and the southern plateau, leaving the largest unbroken spread of alluvium anywhere. How that trough formed is argued: Sydney Burrard proposed a crustal rift, which Richard Oldham and others rejected, while newer work links it to folded Tethys seabed and the uplift of the Himalayas above hard crystalline bedrock. The Delhi Ridge, an arm of the Aravalli Hills, splits the drainage between the Indus to the west and the Ganga–Brahmaputra to the east.
Moving south from the foothills come four bands. Bhabar, only 7 to 15 kilometres wide, is so stony and porous that streams vanish underground; they resurface in the rainy, forested Terai. Below lies Bangar, older alluvium forming the richest farmland, and then Khadir, low ground of fresh silt. Rainfall drops from about 130 centimetres near the mountains toward the Thar Desert in the west, so wheat, barley and millet grow in the dry west and rice in the wet east. The Ganges Plain alone covers 375,000 square kilometres, and the Indus delta shelters the largest arid mangroves on the planet.
People of the Indus Valley Civilisation farmed here by 3000 BCE, and Vedic texts named it Aryavarta, the land between the Himalaya and the Vindhyas. The Maurya empire, ruling from the fourth to the second century BCE, unified most of the subcontinent, and the Guptas of the fourth to seventh centuries CE are remembered for art and science.
Prithviraj Chauhan beat Shihabuddin Ghori at Tarain in 1191 but lost the rematch, opening the way for the Delhi Sultanate. Babur came through the Khyber Pass in 1526 to found the Mughal Empire. After victories at Plassey in 1757 and Buxar in 1764, the East India Company dominated the lower Ganges, and British rule lasted until independence in 1947.
Source: Indo-Gangetic Plain
