Karez systems are the crystallization of ancient people's diligence and intelligence. At its peak, this irrigation system exceeded 5,000 km (3,106 miles) and was also referred to as 'the underground Great Wall'. It is among the three ancient major irrigation projects with the other two being Ling Canal and Dujiangyan Irrigation Project.
Karez systems are the life source of Turpan. In a sense, without them, there would be no Turpan culture. According to records, the history of the karez in Xinjiang dates back to 103B.C. Currently there are still over 400 systems.