Uyghur Karezes Documentary

Karez is an underground water system. Peoples digged beveled underground tunnels and bringed snow water far away from mountains to the desert where they were living. The karez was created for Jiaohe antique city. Today it is the world's utmost ruins of soil city. The whole city is underground. The humanity ignored karez and Jiaohe for centuries. However these are wonders of civilization. The people who invented the system had a culture of long standing. The people consecrated nature and mummified their deads. The karez system required an advanced engineering and great organization. How functions the system which transforms the desert into a forest? Who and when constructed the system? This culture effected The Silk Road and was spread far away both in east and west.