Xinjiang (Uyghur: شىنجاڭ‎, ULY: Shinjang; Mandarin pronunciation: [ɕíntɕjɑ́ŋ]; Chinese: 新疆; pinyin: Xīnjiāng), officially the Xinjiang Uyghur Autonomous Region, is a provincial-level autonomous region of China in the northwest of the country. It is the largest Chinese administrative division and the eighth largest country subdivision in the world, spanning over 1.6 million km2 (0.64 million square miles).[1] Xinjiang contains the disputed territory of Aksai Chin, which is administered by China. Xinjiang borders the countries of Mongolia, Russia, Kazakhstan, Kyrgyzstan, Tajikistan, Afghanistan, Pakistan and India. The rugged Karakoram, Kunlun, and Tian Shan mountain ranges occupy much of Xinjiang's borders, as well as its western and southern regions. Xinjiang also borders Tibet Autonomous Region and the provinces of Gansu and Qinghai. The most well-known route of the historical Silk Road ran through the territory from the east to its northwestern border. In recent decades, abundant oil and mineral reserves have been found in Xinjiang, and it is currently China's largest natural gas-producing region. It is home to a number of ethnic groups, including the Han, Kazakhs, Tajiks, Hui, Uyghur, Kyrgyz, Mongols, and Russians.[6] More than a dozen autonomous prefectures and counties for minorities are in Xinjiang. Older English-language reference works often refer to the area as "Chinese Turkestan".[7] Xinjiang is divided into the Dzungarian Basin in the north and the Tarim Basin in the south by a mountain range. Only about 9.7% of Xinjiang's land area is fit for human habitation.[8] With a documented history of at least 2,500 years, a succession of peoples and empires have vied for control over all or parts of this territory. The territory came under the rule of the Manchu Qing dynasty in the 18th century; which was later replaced by the Republic of China government. Since 1949, it has been part of the People's Republic of China following the Chinese Civil War. In 1954, Xinjiang Bingtuan was set up to strengthen the border defense against the Soviet Union, and also promote the local economy. In 1955, Xinjiang was turned into a autonomous region from a province. In the last decades, a separatist conflict has plagued the region, with occasional terrorist attacks and clashes between separatist and government forces.