a desert in E Asia, mostly in Mongolia and the Inner Mongolian Autonomous Region of China: sometimes considered to include all the arid regions east of the Pamirs and north of the plateau of Tibet and the Great Wall of China: one of the largest deserts in the world. Length: about 1600 km (1000 miles).Width: about 1000 km (625 miles). Average height: 900 m (3000 ft)