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Multiple extreme droughts likely triggered Indus Valley civilisation's collapse: New study

New Delhi: A series of prolonged and severe droughts lasting more than 85 years each likely led to the gradual collapse of the Indus Valley Civilization (IVC), according to a new study published in Nature . The research, led by IIT Gandhinagar in collaboration with two US universities, shows that repeated drought cycles between 4,450 and 3,400 years ago caused widespread aridification across 65- 91% of the region, ultimately forcing the de-urbanisation of Harappan centres. The Indus Valley Civilisation, one of the world's earliest and most sophisticated, thrived across the Indus floodplains in India and Pakistan. It was known for its advanced water systems and planned cities. In the absence of direct climate records, scientists relied on paleoclimate proxies such as cave deposits, tree rings and ice cores to reconstruct water patterns back then. By integrating high-resolution paleohydrological reconstructions with paleoclimate archives, we identified severe and persistent river droughts lasting decades to centuries that affected the Indus basin, said lead author Professor Vimal Mishra of IIT Gandhinagar. Study traces Koraga tribes ancestry to Indus Valley, finds Proto-Dravidian genetic lineage The study found that drought-like conditions began around 4,440 years ago, followed by multiple extreme droughts exceeding 85 years each between 4,400 and 3,000 years ago. Evidence from Dharamjali Cave further showed recurring summer and winter droughts between 4,200 and 3,970 years ago . Aridification intensified around 4,260 years ago and persisted for more than 300 years, leading to the abandonment of major Harappan cities. Although intermittent winter rainfall initially offered relief, its subsequent decline after 3,300 years ago fragmented Harappan settlements, marking the end of the civilization. The findings offer the strongest evidence yet that climate-driven hydrological stress, and not any sudden catastrophe, was central to the Indus Valley's long, gradual decline. Climate change likely caused the demise of Indus Valley civilisation: Study Walking with the Harappans