How about opening Wikipedia and reading about the subject? I don't owe you any explanation. There is no ambiguity or "disagreement" (except on the Chinese side)

How about opening Wikipedia and reading about the subject? I don't owe you any explanation. There is no ambiguity or "disagreement" (except on the Chinese side) on the matter: the fact is Taiwan has never ever been under the sovereignty of the People's Republic of China, period. The preceding entity that had both control over mainland China and Taiwan was the Republic of China, which is now ruling Taiwan. If for you the fact that a country emits internationally valid passports, print its money, has a government and an army is not enough to be a real state, you're a living in a province of China too.