Silla, Bletilla and Koryo, which moved in from China?

What you asked was the question of the Three Kingdoms period in Korea! It should be Koguryo, not North Korea. These two concepts are completely different. Many Koguryo nationals are descendants of China, because its main borders were in the territory of Han, Cao Wei and Western Jin Dynasty at that time, that is, Korea, Liaoning and Jilin today. Baekje, Silla, too south, China moved in less. Therefore, most historians in China have listed Koguryo as the frontier regime of China, but both North Korea and South Korea protested (see Northeast Project), but South Korea came late and had nothing to do with Koguryo. North Korea is a unified regime on the Korean peninsula.