洮河
Located at an important Tao River crossing, Didao City (i.e., today's Taoyang Town) was an important trade center during the Northern Song Dynasty (ca. 11-12th century), when the more northern route of the Silk Route was blocked by the Xi Xia state. It is known to have been home to hundreds of foreign merchants at the time, some of whom may have been the ancestors of today's Hui people of Gansu.