Indian peninsula environmental history 4,500 years ago

About 4,500 years ago (far left), river flooding allowed the Harappans to farm Indus Valley floodplains and build large cities. People living farther south on the Indian peninsula survived as hunter-gatherers. When the monsoons weakened (left), Indus valley agriculture failed and the Harappans left their cities. The peninsula became more arid, prompting the people there to settle in towns and become farmers.
(Illustration by Amy Caracappa-Qubeck, © Woods Hole Oceanographic Institution)