Gansu lies between the Tibetan Plateau and the Loess Plateau, bordering Mongolia (Govi-Altai Province) to the northwest, Inner Mongolia and Ningxia to the north, Shaanxi to the east, Sichuan to the south, and Xinjiang to the west. The Yellow River passes through the southern part of the province. The province contains the geographical centre of China, marked by the Center of the Country Monument at . Part of the Gobi Desert is located in Gansu, as well as small parts of the Badain Jaran Desert and the Tengger Desert. The Yellow River gets most of its water from Gansu, flowing straight
Gobi Desert as a buffer against further desertification. The Gobi, broadly defined, can be divided into five distinct dry ecoregions, based on variations in climate and topography: The surface is extremely diversified, although there are no great differences in vertical elevation. Between Ulaanbaatar () and the small lake of Iren-dubasu-nor (), the surface is greatly eroded. Broad flat depressions and basins are separated by groups of flat-topped mountains of relatively low elevation ), through which archaic rocks crop out as crags and isolated rugged masses. The floors of the depressions lie mostly between above sea-level. Farther south, between Iren-dutiasu-nor and the Yellow