Indus Valley Civilization Collapse Linked to Century-Scale Droughts

A new study published in Communications Earth & Environment indicates that the collapse of the Indus Valley Civilization (IVC) was significantly linked to a series of prolonged droughts, each lasting over 85 years.

This influential ancient society, which thrived between 5,000 and 3,500 years ago along the Indus River in present-day Pakistan and northwest India, experienced a gradual decline in urban and cultural complexity due to these environmental pressures.

Researchers, led by Vimal Mishra, utilized climate modeling and indirect indicators of ancient climate change, such as chemical signatures from stalactites and water level histories from lakes, to reconstruct the climate patterns of the region.

Their analysis revealed a temperature increase of approximately 0.5 degrees Celsius and a reduction in annual rainfall by 10 to 20 percent during this period. Notably, four extended droughts occurred between 4,450 and 3,400 years ago, affecting 65 to 91 percent of the area associated with the IVC.

These conditions prompted shifts in settlement patterns, with populations moving closer to the Indus River for more reliable water sources as drought intensified. One particularly severe drought lasting 113 years coincided with evidence of widespread deurbanization, suggesting that the civilization's decline was a prolonged process rather than a sudden collapse.

Thus, the study emphasizes the critical impact of long-lasting environmental changes on the sustainability of early civilizations, providing lessons for contemporary societies facing similar climate challenges.