^lol you're missing a huge chunk of the story there.
Maybe start with reading this:
https://en.wikipedia.org/wiki/Chinese_Civil_War
[Chinese History for Dummies] Basically in the first half of the 20th Century two factions were at war in China - The Nationalists (incumbent) and the Communists. After WWII the Japanese are defeated the Nationalists and Communists duke it out again with the Commies winning in 1949 and the Nationalists fleeing to Taiwan (recently handed back to China from Japan). The remnants of which form the government of Taiwan for the next few decades. Since the Nationalists were basically the Chinese government in exile Taiwan is officially known as the "Republic of China" (ROC) However the Communists People's Republic of China (PRC) sees themselves as the legitimate government of China since they hold 95% of it's territory. Most Western countries still recognized ROC as the legitimate government since they were staunchly anti-communist. In the 1970s Nixon visits China to thaw relations and to use their relationship as a counterweight to the Soviets - start to recognize PRC over the ROC. Most of the UN nations follow suit in the coming years and kick out the ROC out of the UN in favor of the PRC.