Climate change -- not Genghis Khan -- caused the demise of Central Asia's river civilizations, research shows

Summary:

While Genghis Khan and Mongol invasion is often blamed for the fall of Central Asia's medieval river civilizations, new research shows it may have been down to climate change. Researchers conducted analysis on the region and found that falling water levels may have led to the fall of civilizations around the Aral Sea Basin, as they depended on the water for irrigation-based farming.

Date: December 15, 2020

Source: University of Lincoln

Ruins of Otrar, Kazakhstan (stock image).
Credit: © Dmitry Chulov / stock.adobe.com

A new study challenges the long-held view that the destruction of Central Asia's medieval river civilizations was a direct result of the Mongol invasion in the early 13th century CE.

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 irrigation to farm.

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.

Research led by the University of Lincoln, UK, 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.

Mark Macklin, author and Distinguished Professor of River Systems and Global Change, and Director of the Lincoln Centre for Water and Planetary Health at the University of Lincoln said: "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.

"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."

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 present 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 was led by the University of Lincoln in collaboration with VU University Amsterdam, University College London, the University of Oxford and JSC Institute of Geography and Water Safety, Almaty, Republic of Kazakhstan. It is published in Proceedings of the National Academy of Sciences of the United States of America and highlights the critical role that rivers can have in shaping world history.

Story Source:
Materials provided by University of Lincoln. Note: Content may be edited for style and length.

Journal Reference:
Toonen, W.J.H., Macklin, M.G., Dawkes, G., Durcan, J.A., Leman, M., Nikolayev, Y. and Yegorov, A. A hydromorphic reevaluation of the forgotten river civilizations of Central Asia. Proceedings of the National Academy of Sciences, 2020 DOI: 10.1073/pnas.2009553117

University of Lincoln. "Climate change -- not Genghis Khan -- caused the demise of Central Asia's river civilizations, research shows." ScienceDaily. ScienceDaily, 15 December 2020. <www.sciencedaily.com/releases/2020/12/201215112017.htm>.