People's Republic of China (PRC) didn't. It is a counterattack in self-defense, the Vietnam War, and the War to Resist US Aggression and Aid Korea. There was no territorial occupation after the war. In ancient history, Vietnam in the Qin Dynasty was once called Baiyue or Nantian Kingdom. Anyway, it's Southeast Asia. Even in the Spring and Autumn Period and the Warring States Period, the territory of Chu and Vietnam overlapped, and the North Yan State was close to the Korean Peninsula. In the Han Dynasty, North Korea was within the territory of the Han Dynasty, and now the position of South Korea is generally absent. The Korean peninsula has always been a divided place, and it has been divided for most of the time, about two or three countries.