What happened to the Indus Valley Civilization?
The Indus Valley Civilization declined around 1900 BCE and was gradually abandoned over several centuries. The exact causes remain debated, but likely factors include climate change causing drought, the shifting course of the Sarasvati River, disrupted trade networks, and possible tectonic activity.
The decline and abandonment of the Indus Valley Civilization is one of ancient history's greatest mysteries. At its peak around 2500 BCE, it was the largest civilization in the Bronze Age world — larger than Egypt and Mesopotamia combined — with sophisticated cities like Harappa and Mohenjo-daro housing tens of thousands of people. By 1700 BCE, these great cities were largely abandoned.
Several factors likely contributed to the decline. Climate science has revealed a significant shift in monsoon patterns around 2000-1900 BCE, reducing rainfall and river flow across the region. The Ghaggar-Hakra river system — which many scholars identify with the ancient Sarasvati River — may have dried up or changed course, removing a critical water source for cities and agriculture.
Some scholars point to tectonic activity that may have disrupted river courses and caused flooding. The disruption of long-distance trade networks — Indus goods are found in Mesopotamia, and vice versa — may have undermined urban economies dependent on commerce. There is no clear evidence of violent conquest, though some sites show signs of increased stress and conflict in their final phases.
The decline was not sudden but gradual. People didn't disappear — they dispersed. Population shifted from large urban centers to smaller rural settlements, particularly in the east and south. Cultural traditions continued in modified form. The Indus civilization didn't collapse so much as it de-urbanized, its people adapting to changing environmental and economic conditions.