Xinjiang is the largest political subdivision of China—it accounts for more than one sixth of China's total territory and a quarter of its boundary length. Xinjiang is mostly covered with uninhabitable deserts and dry grasslands, with dotted oases at the foot of Tian Shan, Kunlun Mountains and Altai Mountains. The inhabitable oasis accounts for 9.7% of Xinjiang's total area by 2015.