Did Koreans migrate there from ancient China?

Yes, it is exactly the developer of North Korea. Why did I say North Korea and not South Korea as you asked?

North Korea has experienced Jizi North Korea, Weiman North Korea, and the Three Kingdoms of North Korea. Era (Goguryeo, Silla, Baekje), the Unified Silla Era, the Northern and Southern Kingdoms Era, the Post-Three Kingdoms Era, the Goryeo Dynasty, the Joseon Dynasty, the Korean Empire, the Japanese occupation era, and the U.S.-Soviet military and political era [2]. During World War II, the Korean Peninsula was divided into North Korea and the Republic of Korea.

In fact, today's South Korea and North Korea are of the same family

The earliest two dynasties of North Korea were founded by the Chinese

Jizi is the son of Wen Ding , the younger brother of Emperor Yi, the uncle of King Zhou, the official grand master, was granted the title of Ji (now in the Yushe area of ??Taigu, Shanxi), and his name was Xu Yu. As the first philosopher in China, he was a great figure in the era of the alternation of Shang and Zhou regimes and the great historical turmoil. Among them, because his ways could not be carried out and his ambitions could not be fulfilled, he "violated the fate of the Yin Dynasty and went to Korea" and established the Eastern Gentleman Kingdom, whose legacy still exists today.

Ji Zi is indeed a real person. There is no doubt that three famous figures of the Yin and Shang Dynasties, Bigan was killed, and Weizi was granted the title of Song Dynasty. Why is it suspected that Jizi went to North Korea? Moreover, if he did not go to North Korea, why is there no information suggesting Jizi's other whereabouts? What? There are roughly two types of history of exchanges between nations around the world: one is peaceful exchanges; the other is conquest and resistance by force. Jizi's entry into Korea belongs to the former type; Weiman's invasion and Emperor Wu's conquest belong to the latter type. Jizi's entry into North Korea laid the foundation for thousands of years of cultural exchanges and friendship between China and North Korea. Therefore, ancient Korean traditional history books have always affirmed the development of Jizi and regarded the Ji dynasty as orthodox; they have adopted a critical attitude towards Weiman. Because Jizi and his descendants not only contributed to the development of the peninsula, but also became part of the ancient Korean nation and were universally recognized.