Gansu is sometimes said to be the most complex among the provinces of China. It is 1655 km long from east to west, and 530 km wide from north to south. It has six distinctive regions: Longnan Mountains, Longzhong Loess Plateau, Gannan Plateau, Hexi Corridor, Qilian Mountains, and the desert north of the Hexi Corridor. Most of the province is mountainous and plateaus.
Tianshui City in Gansu Province is called the grottoes corridor of the eastern part of the Silk Road. There are six groups of grottoes there: Maiji Grottoes, Daxiang Mountain Grottoes and Huagaisi Grottoes in Gangu Valley, and Shuilian Cave Grottoes, Mutisi Grottoes and Chandiansi Grottoes at Wushan Mountain. The grottoes at Mutisi, Daxiangshan and Shuiliandong are listed as Major National Historical and Cultural Sites in Gansu.