China is the largest country located entirely within Asia, covering over 3.7 million square miles. The greater part of the country is mountainous. Its principal ranges are the Tien Shan, the Kunlun chain, and the Trans-Himalaya. In the southwest is Tibet, which China annexed in 1950. The Gobi Desert lies to the north. China proper consists of three great river systems: the Yellow River (Huang He), 2,109 mi (5,464 km) long; the Yangtze River (Chang Jiang), the third-longest river in the world at 2,432 mi (6,300 km); and the Pearl River (Zhu Jiang), 848 mi (2,197 km) long. It has an extensive coastline on the Pacific Ocean.

China shares borders with fourteen neighboring countries. In order of shared border length, these are: Mongolia (4,630km), Russia (Northeast - 4,133km) and (Northwest - 46km), India (2,659km), Myanmar (2,129km), Kazakhstan (1,352km), Nepal (1,389km), North Korea (1,352km), Vietnam (1,297km), Kyrgyzstan (1,063km), Tajikistan (477km), Bhutan (477km), Laos (475km), Pakistan (438km), and Afghanistan (91km).

source: infoplease.com