A series of century-scale droughts may have quietly reshaped one of the world’s earliest urban civilizations. New climate reconstructions show that the Indus Valley Civilization endured repeated long dry periods that gradually pushed its people toward the Indus River as rainfall diminished. These environmental stresses coincided with shrinking cities, shifting settlements, and eventually widespread deurbanization. Rather than a dramatic collapse, the civilization appears to have faded slowly under relentless climate pressure.

Severe and persistent river droughts, each lasting longer than 85 years, affected the Indus basin between 4,400 and 3,400 years ago, according to new research.