How many years have Taiwan Province Province and Nanhai belonged to China respectively?

Taiwan Province Province officially became the territory of China from the Yuan Dynasty, when Taiwan Province Province was under the jurisdiction of Penghu Inspection Department. About 700 years ago.

In fact, there was no concept of maritime boundary in ancient China. At that time, the South China Sea only referred to the offshore area of the continental margin. If the South China Sea Islands are mentioned, they probably belong to the Qing Dynasty, and some should be later.