The Qinghai–Tibet Plateau above 4,000 m, plateaus and basins at 1,000–2,000 m, plains and hills below 500 m — China is a giant staircase descending from west to east.
Slice China along the 32nd parallel and the cross-section shows three steps: the first, the Qinghai–Tibet Plateau averaging over 4,000 meters; the second, plateaus and basins at 1,000–2,000 meters; the third, plains and hills below 500 meters. The land falls from west to east like three tiers of grandstands facing the ocean.
The Qinghai–Tibet Plateau averages more than 4,000 meters and covers about a quarter of China — the highest great plateau on Earth, the “roof of the world.” On its southern rim stands Mount Qomolangma (Everest) at 8,848.86 m, the highest point on the planet; on the same plateau sit Qinghai Lake and the Changtang grassland.
The plateau is the water tower of Asia: the Yangtze, the Yellow River, the Lancang (Mekong), the Yarlung Tsangpo (Brahmaputra), the Ganges and the Indus all rise here or pass through. Its glaciers and snowfields supply water to billions of people across China and South Asia.
On the second step sit the Inner Mongolia, Loess and Yungui plateaus and the four great basins — Tarim, Junggar, Qaidam and Sichuan. China’s pastoral lands, its dry-farming loess country and the “Land of Abundance” all belong to this tier.
The third step is the Northeast Plain, the North China Plain, the middle-lower Yangtze plains and the southeastern hills, mostly under 500 meters. More than four-fifths of China’s people and nearly all of its megacities crowd onto this lowest step — because it is flat, watered and fertile.
The line between steps one and two runs through the Kunlun, Qilian and Hengduan mountains; between steps two and three, through the Greater Khingan, Taihang, Wu and Xuefeng mountains. Nobody drew these lines — they are the edges left by the uplift and sinking of the crust.
The cities on the lines feel the staircase directly: Lanzhou sits at the lip of the second step, and the road down to Xi’an descends more than a kilometer. The Three Gorges Dam sits precisely at the junction of steps two and three, generating power from the drop — which is why China’s great hydropower stations grow along the edges of the staircase.