Answer:
China entered the Korean War on the side of North Korea, which changed the course of the war. In October 1950, Chinese troops crossed the Yalu River to help North Korea in the war. This was a big turning point in the war because it gave North Korean forces a chance to reorganize and push back against UN forces that had moved deep into North Korea. The Chinese involvement also led to a long, bloody standstill that lasted until 1953, when an armistice was signed.