How do Chinese write “China” in Chinese? It’s a basic but very important question. There is only one answer for this question: 中国（zhōng guó）. The first character means “center”， and the second character means “country” or “nation”. All Chinese use the same words so you need to worry about get confused.
As for the history of this word, it can be traced from the Persian traders during the Qin dynasty in early 200 B.C.. But it was not become a official words until han dynasity. In the Han Dynasty, the Central Plains dynasty established by the Han nationality and the Central Plains dynasty established by the fraternal nations were both called “China”. During the Southern and Northern Dynasties, the Northern Wei Dynasty called itself “China”, but called the Southern Dynasty “Island”. That’s strange, right? Liao and Northern Song, Jin and Southern Song Dynasity all called themselves as “China” and did not recognize each other as “China”.
That’s is to say, “China” means a country dominating other regions in the old times. Now, there is only one “China” in the world, which is the People’s Republic of China.