King Geunchogo of Baekje (?-375, reigned 346-375) was the 13th king of the ancient Korean kingdom of Baekje, one of the Three Kingdoms of Korea. He was the second son of King Biryu, and his reign seems to have marked the permanent ascendancy of the descendants of King Saban over those of King Goi. He was named after his ancestor, King Chogo.

Upon ascending the throne, he set out to solidify the royal power within the Baekje state. He reduced the power of the aristocracy and set up a system of local government. He married a wife from the Jin clan, setting a precedent for his descendants.

Under King Geunchogo, the kingdom reached its greatest geographic extent and political power. This marked the apex of the Baekje's Han River period. The tribes of Mahan were all brought under Baekje's sway in the year 369. In the same year, Baekje was invaded by Goguryeo, but counterattacked in force. In the year 371, the Baekje army took the fortress of Pyongyang and killed King Gogugwon of Goguryeo. The Gaya states were also made into Baekje dependencies. At the end of these conquests, Baekje ringed the West Sea (Yellow Sea), and controlled much of the Korean peninsula.

King Geunchogo also imported Chinese culture and learning from the Eastern Jin Dynasty, and exported it in turn to Baekje's allies in the Wa kingdom of Yamato period Japan. According to both Korean and Chinese sources, the first diplomatic contact between Baekje and China took place in 372, when Geunchogo sent a mission to the court of Jin. In the same year, the Jin court sent a mission granting him the title of "General Stabilizing the East and Administrator-General of Lelang."

Also during his reign, a history of Baekje called Seogi (서기, 書記) was compiled by the scholar Go Heung (고흥, 高興). It has not survived.

See also

• History of Korea
• List of Korea-related topics