Final answer:
Chiang Kai-shek fled to Taiwan after losing the Chinese civil war and established the government of the Republic of China (ROC) there, which was recognized by the United States and other Western countries as the legitimate government of all China until 1971.
Step-by-step explanation:
Jiang Jieshi, also known as Chiang Kai-shek, established the government of Taiwan after fleeing the mainland when Mao Zedong and the Communist Party of China won the civil war in 1949. The island of Taiwan was declared the official Republic of China (ROC), continuing the Nationalist government. Western powers, particularly the United States, supported Chiang's government due to Cold War politics, recognizing it as the legitimate government of all China and allowing it to hold China's seat in the United Nations until 1971 despite the fact that the Communists controlled the mainland.