Four Commanderies of Han

The Four Commanderies of Han were Chinese commanderies established in the northern Korean Peninsula and part of the Liaodong Peninsula from the end of the second century BCE through the early 4th century CE. They were set up by Emperor Wu of the Han dynasty in the early 2nd century BCE after he conquered Wiman Joseon, and were seen as Chinese colonies in the former Gojoseon region, reaching as far south as the Han River. Lelang, Lintun, Zhenfan, and Xuantu were the commanderies created, with Lelang being the most long-lasting and a significant center of cultural and economic exchange with subsequent Chinese dynasties. Over time, three of the commanderies fell or retreated, but Lelang remained for four centuries, influencing the native population and eroding the fabric of Gojoseon society. Goguryeo, founded in 37 BCE, began absorbing these commanderies into its territory by the early 5th century.

Initially, after Gojoseon's defeat in 108 BCE, the three commanderies of Lelang, Lintun, and Zhenfan were established, with Xuantu Commandery being founded in 107 BCE. By the 1st century CE, Lintun merged into Xuantu, and Zhenfan into Lelang. In 75 BCE, Xuantu moved its capital due to local resistance. The commanderies, especially Lelang, established trade relations with neighboring Korean states like Jinhan and Byeonhan. As indigenous groups integrated with Han culture, a unique Lelang culture emerged in the 1st and 2nd centuries CE.

Gongsun Du, a significant figure from the Liaodong Commandery, expanded into Goguryeo territories and exerted dominance in the northeast. His reign saw confrontations with Goguryeo and expansions into its lands. After his death in 204, his successors continued to assert their influence, with Gongsun Kang even annexing parts of Goguryeo in the early 3rd century. However, by the late 3rd century, Sima Yi of Cao Wei invaded and took over their territories. Following the fall of the Han commanderies, Goguryeo grew stronger, eventually conquering the Lelang, Daifang, and Xuantu commanderies by the early 300s.