Climate change destroyed river civilisations, not Genghis Khan’s horsemen – study

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An abandoned medieval canal in the Aral Sea basin in Central Asia.

Genghis Khan and his marauding Mongol horsemen were probably not responsible for the demise of Central Asia’s medieval river civilisations around 700 years ago, fresh research suggests.

Instead, climate change was to blame, according to research led by the University of Lincoln in England.

The Aral Sea basin in Central Asia and the major rivers flowing through the region were once home to advanced river civilizations which used floodwater to irrigate farmland.

The region’s decline is often attributed to the devastating Mongol invasion of the early 13th century, but new research of long-term river dynamics and ancient irrigation networks shows the changing climate and dryer conditions may have been the real cause.

Researchers reconstructed the effects of climate change on floodwater farming in the region and found that decreasing river flow was equally, if not more, important for the abandonment of these previously flourishing city-states.

“Our research shows that it was climate change, not Genghis Khan, that was the ultimate cause for the demise of Central Asia’s forgotten river civilizations,” said Mark Macklin, distinguished professor of river systems and global change at the university.

“We found that Central Asia recovered quickly following Arab invasions in the 7th and 8th centuries CE because of favourable wet conditions. But prolonged drought during and following the later Mongol destruction reduced the resilience of local population and prevented the re-establishment of large-scale irrigation-based agriculture.”

Reconstruction of a Mongol warrior from Genghis Khan: The Exhibition. Photo: William Cho CC BY-SA via Wikimedia Commons

The research focused on the archaeological sites and irrigation canals of the Otrar oasis, a UNESCO World Heritage site that was once a Silk Road trade hub located at the meeting point of the Syr Darya and Arys rivers in what is now southern Kazakhstan.

The researchers investigated the region to determine when the irrigation canals were abandoned and studied the past dynamics of the Arys river, whose waters fed the canals.

The abandonment of irrigation systems matches a phase of riverbed erosion between the 10th and 14th century CE, that coincided with a dry period with low river flows, rather than corresponding with the Mongol invasion.

The research involved the University of Lincoln in collaboration with VU University Amsterdam, University College London, the University of Oxford and the JSC Institute of Geography and Water Safety at Almaty, in Kazakhstan.

The findings have been published in the Proceedings of the National Academy of Sciences of the United States of America. The research highlights the critical role that rivers can have in shaping world history.

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