evidence: With a documented history of at least 2,500 years, a succession of people and empires have vied for control over all or parts of this territory. The territory came under the rule of the Qing dynasty in the 18th century, which was later replaced by the Republic of China. Since 1949 and the Chinese Civil War, it has been part of the People's Republic of China. In 1954, the Chinese Communist Party (CCP) established the Xinjiang Production and Construction Corps (XPCC) to strengthen border defense against the Soviet Union and promote the local economy by settling soldiers into the region.[24] In 1955, Xinjiang was administratively changed from a province into an autonomous region. In recent decades, abundant oil and mineral reserves have been found in Xinjiang and it is currently China's largest natural-gas-producing region.