After the Communist victory in China, the Nationalists go to the island of Taiwan and set up a rival government.
The USA recognises Taiwan as the legitimate government of China. The USSR recognises the government of mainland China. The two main superpowers have created two Chinas. Taiwan gets the single seat in the United Nations (because of American pressure) even though it contains less than 1% of the population. Taiwan is backed and supported by the USA even though, it bans all political parties until 1987. Mainland China, representing a fifth of the world's population, would not be allowed to join the United Nations until 1971.
Many Nationalists take refuge in northern Burma where CIA advisors arm them for incursions into China.