China’s vast territory includes plateaus, plains, basins, foothills, and mountains. Plateaus, foothills and mountains occupy nearly two-thirds of the land, higher in the West and lower in the East like a three-step ladder. The highest step of the typical “ladder topography” is formed by the Qinghai-Tibet Plateau with an average height of over 4 000 meters. On the second step are large basins and plateaus, most of which are 1 000-2 000 meters high. The third step, abundant in broad plains, is dotted with foothills and lower mountains, with altitudes of over 500 meters.