The Karez is an underground irrigation system that was constructed over 2,000 years ago and is considered 1 of the greatest engineering achievements of ancient China, with the Great Wall and the Grand Canal.
It is a series of wells and underground channels that transferred water, usually from the glaciers on the base of the Tian Shan, to communities in the area. Many cities on the ancient Silk Road, some as far west as modern Iran, relied on this irrigation system as a primary supply of water
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