Im interested in your POV on the disputed territory with Korean nationalists that made up the ancient Kingdom of Goguryeo Part of which now forms part of Chinese territory
If I applied Iron Man's logic the people of Korean/Goguryeo heritage that live there may strongly object to being refered to as Chinese.
That is the un-mendable gap between me and Iron Man, his logic is based on the morden western defination of the word "China" which is not "中国". "中国" is the term that was used by the people in East asia to refer to various Chinese dynasties and their territoris and subjects. It literally means "Middle State". Very often Koreans and Japanese might also use the term in their own languages to refer their dynasties. You can find Japanese historical records to refer to the area around the capital (Kyoto) as 中国.
Once again, the only firm term referring territory of a state in east Asia was the name of the dynasties.
Another example is Korea, the name is one of the many dynasties on that parnisular, for most of the time, they are referred as Chaoxian (Chuson). Today's North Korea is still officially refered and self-refered as "Chuson", NOT Korea. It would be rediculous if we apply Iron Man's logic on the Koreans by stating "the Koreans strongly object to be refered as Chusonians" or vise versa.
One more example is Vietnam. For that, I leave it to you to checkout. Just a short note, Vietnam is a name of one dynasty in recent history.
To your specific sentence, what is "Chinese" in the acient time (Goguryeo times)? That word did not exist. It was not an issue for people at that time.
If you mean Han by the word Chinese, people of Korean/goguryeo heritage are surely not Han, and they are NOT referred as Han inside PRC. Not an issue for them.
If you mean citizen of PRC, then they are surely a citizen which is called "中国公民".
Remember inside 中华人民共和国 we speak Mandarin (a Han dialect), and we call every citizen 中国人. If you (or rather Iron Man) ask those people that question, you must speak Mandarian to them, they would not have any idea what you mean by "Chinese". (no intention of mocking, just give you the picture of reality).