you know nothing about china-korea historic relationship.
Korea had been imperial china's vassales for over 1000 years before sino-Japan war in 1895.
before the 4th century,North Korea was even directly- ruled chinese provinces.
Vassal relationship is symbolic, not territorial nor economic(no regular taxes to pay.) Mongol Empire was an exception to this.
You mean, China had some outlying administrative areas in Liao-dong/Liao-shi back before 4th century AD. It was not near Pyongyang area as some argue.
This things come and ago. This area changed hands many times.
Old Chosun had it. Han Dynasty had it. Xianbei had it. Koguryo had it. Balhae had it. Khitan had it. Jurchen Chin had it. Mongol had it. Ming Dyansty had some garrisons there.
It goes on.
America was our Korean Territory 1000 years ago!
Japan was our Land before 1935!
America was our Territory 1000 years ago!
Japan was our Land before 1935!