Chinese legitimacy question (Chinese: 中國代表權問題) is the question regarding the political legitimacy of representing "China", and what polity is considered as "legitimate government of China" or "legitimate representative of China".
From 1911 to 1949, the representation of "China" on the world stage unambiguously belonged to the Republic of China. On October 1, 1949, Mao Zedong officially announced the proclamation of the creation of the People's Republic of China. From then on, two distinct polities, the Republic of China (ROC – which had retreated to Taiwan) and the People's Republic of China (PRC – which now controls mainland China) both claim to be the only legitimate representative of "China".
In 1971, the UN General Assembly passed Resolution 2758, where the PRC officially replaced the ROC's former seat at the UN, including its permanent member status at the security council. Since then, most countries in the world formally recognize the PRC as the representative of China, though many still maintain informal relations with the ROC.
Since the creation of the PRC, the political status of Taiwan has been in dispute. According to the PRC, the UN resolution's recognition of representation extends also to Taiwan, which is why the PRC should be the legitimate representative. However, the ROC disputes this, and historically claimed to be the representative of China in line with its One China principle. However, the government has in recent years been more accepting of the Two Chinas reality based on the 1992 Consensus.