Turpan is the place on the northern Silk Road where history is most visible. The Jiaohe and Gaochang ruins are walled cities that grew while caravans crossed the Tianshan foothills, and their earth walls, temple foundations and streets can still be read on the ground.
The basin is why the oasis exists. The Turpan depression lies well below sea level, with very low rainfall and a hot summer, yet the valley is green. Water comes from snowmelt in the Tianshan, carried by the karez, an underground canal system that has watered vineyards for centuries.
