Xinjiang Province () or Sinkiang Province was a province of the Republic of China (ROC) from 1912 to 1992. Its existence was nominal after the ROC's defeat in the Chinese Civil War and the subsequent incorporation of Xinjiang into the People's Republic of China (PRC) in 1949. The provincial government relocated to Taipei and was reorganized as the Sinkiang Provincial Government Office (), but it was without administrative function. In the PRC, Xinjiang Province was replaced by the Xinjiang Uyghur Autonomous Region in 1955.
The province inherited the borders of the Qing dynasty province, bordering Kansu, Tsinghai, the Mongol Area, Tibet Area and the countries Soviet Union, Afghanistan, India and Pakistan. The claimed boundaries of the province included all of today's Xinjiang and parts of Mongolia, Tajikistan, Afghanistan and Pakistan.
In 1912, the Qing dynasty was replaced by the Republic of China. Yuan Dahua, the last Qing governor of Xinjiang, fled. One of his subordinates, Yang Zengxin, took control of the province and acceded in name to the Republic of China in March of the same year. Through Machiavellian politics and clever balancing of mixed ethnic constituencies, Yang maintained control over Xinjiang until his assassination in 1928 after the Northern Expedition of the Kuomintang.
The Kumul Rebellion and other rebellions arose against his successor Jin Shuren in the early 1930s throughout Xinjiang, involving Uyghurs, other Turkic groups, and Hui (Muslim) Chinese. Jin drafted White Russians to crush the revolt. In the Kashgar region on November 12, 1933, the short-lived self-proclaimed First East Turkistan Republic was declared. The Hui Kuomintang 36th Division (National Revolutionary Army) destroyed the army of the First East Turkestan Republic at the Battle of Kashgar (1934), bringing the Republic to an end. The Soviet Union invaded the province in the Soviet Invasion of Xinjiang. In the Xinjiang War (1937), the entire province was brought under the control of northeast Manchu warlord Sheng Shicai, who ruled Xinjiang for the next decade with close support from the Soviet Union. In 1944, the President and Premier of China, Chiang Kai-shek, informed by the Soviets of Sheng's intention to join the Soviet Union, decided to shift him out of Xinjiang to Chongqing as the Minister of Agriculture and Forest. More than a decade of Sheng's era had ended. However, a short-lived Soviet-backed Second East Turkestan Republic was established in that year, which lasted until 1949 in what is now Ili Kazakh Autonomous Prefecture (Ili, Tarbagatay and Altay Districts) in northern Xinjiang.
During the Ili Rebellion the Soviet Union backed Uyghur separatists to form the East Turkestan Republic (ETR) in Ili region while the majority of Xinjiang was under the control of the Republic of China. In 1946, the ROC government and the ETR agreed to establish the Coalition Government of Xinjiang Province, although it collapsed shortly after in 1947. The People's Liberation Army entered Xinjiang in 1949 and the Kuomintang commander Tao Zhiyue surrendered the province to them. The original provincial government was relocated to Taipei as the Sinkiang Provincial Government Office (æ°çÂÂçÂÂæ¿åºÂ辦äºÂèÂÂ) to symbolize the ROC's claim of sovereignty over the province; it was eventually dissolved in 1992.