After the assassination of King Bunseo by the Han Commanderies, Baekje remained relatively stable for the next forty years under King Biryu. Biryu was a relative of King Saban, the monarch whom Go-I forced to step down. From then on the two descendants, the Go-I and Saban lines, competed for kingship. Biryu took power under circumstances similar to how Saban lost his- by claiming that Bunseo’s successor was too young to rule. Biryu died in 344, and the successor took his position as King Gye. He only reigned for two years, and was the last king to be descended from Go-I. The short and uneventful reign gave way to Baekje’s most important ruler. 346 was a monumental year for Baekje, beginning its crescendo to become the super power of the peninsula, led by King Geunchogo.
For such an influential figure, the records tell us surprisingly little about the king. The Samguk Sagi only has a few entries about his reign, but every entry is a lifetime’s worth of accomplishments.
In the second year of his rule, King Geunchogo performed the sacrifices to heaven and his ancestors, and then set out on his work. He continues King Biryu’s diplomatic efforts to ally with Silla, and by 366 Silla and Baekje were regularly sending envoys to one other. Gaya and Baekje were also on good terms.
As for Goguryeo, the situation in the northern country was not going well. Goguryeo had suffered a humiliating blow from the Murong Xianbei. Since the Xianbei were pressing down from the northern regions, Goguryeo looked south to the newly unoccupied southern regions where the Daebang commaderies were. Baekje also had sights on this new land, and the two countries fought the battle of Chiyang in 369. Baekje showed an unexpected force and the Goguryeo army retreated. King Geunchogo, in a show of immense confident, plotted a counter attack in the heart of the northern kingdom. He fitted his army with imperial yellow (a color traditionally reserved for the Emperor of China) flags and, two years after Chiyang, marched an army of three hundred thousand to Pyeongyang. Two centuries earlier an army of twenty thousand was enough to intimidate the first Chogo of Baekje. Now his successor by name (the “Geun” in Geunchogo denotes second, to show his alliance with the old family line) managed to raise an army almost ten times as big.
The army attacked the Pyeongyang fortress, forcing the Goguryeo king to lead an army to repel the invaders. King Geunchogo’s son, the succeeding King Geungusu, drew his arrow and fatally wounded the Goguryeo monarch. Although Baekje retreated soon afterwards, this battle in 371 culminated in Baekje’s dominance over the region.
Although still smaller than Goguryeo, Baekje gained significant amounts of land under Geunchogo’s reign. Source: Wikipedia.
Baekje then set sights on improving ties with its neighboring countries. First order of business: China. This was a politically tumultuous era (see King Micheon’s entry for further details), and the Jin, successors to the Cao Wei, had lost a lot of land and power to the invading northern countries. In addition, the dismantling of the Han Commanderies cut them off from prospective trading and diplomatic relations with the countries to the east. So we might suppose that the Jin court warmly greeted Geunchogo’s envoys in 372. Baekje and Jin had set up official relations, Geunchogo married a woman from the Jin court, and the Jin bestowed to Geunchogo the title of “General Stabilizing the East and Administrator General of Lelang.” This put Baekje in a favorable position to step up diplomacy with another neighboring country.
Geunchogo’s most long lasting achievement might probably be his efforts to normalize relations with the Yamato (usually referred to as the Wa in Chinese and Korean historical texts), modern day Japan. Japan’s historical texts record a few instances of their alliance. One of the most famous symbols of this relation is the Seven Branched Sword, counted among Japan’s national treasures. The sword will be very familiar to anyone interested in Japanese pop culture, since it appears in many games, movies, manga and anime as a powerful weapon (although the real sword was most likely strictly ornamental).
King Geunchogo, or one of his successors, also sent the scholars Ajiki and Wang In. They brought literacy of Chinese characters to the Yamato court, and instructed them in the Confucian classics. It’s never mentioned when Baekje gained reading and writing, but it was in use, if only by an elite few, by Geunchogo’s time. In fact, Geunchogo commissioned the scholar Goheung to write a history of Baekje. The Seogi, as it was called, was the first historical text written in Korea. Sadly no remaining copies exist today.
A lot of modern historians consider the 4th century to be the beginning of the Three Kingdoms period. They mention the legends of the three founders (Jumong, Onjo and Pak Hyeokgose) in passing, and then skip a few centuries to Baekje’s expanding power. Geunchogo’s reign was a watershed moment in early Korean history. He changed Baekje’s position in the peninsula and, if there is any truth to the “Continental Baekje” theory, it might probably be because Baekje had trading outposts on the continent at the time, showing it to be an active player in the politics of the day. King Geunchogo died in 376, leaving Baekje, Goguryeo, Silla, Gaya and Japan involved in intrigues and alliances which would very quickly become the conflicts of the three kingdoms.
King Geunchogo is one of the important figures that people learn about in schools, and is featured prominently in textbooks. Because of the lack of any entries on his personal life, Geunchogo doesn’t show up in pop culture very often. There was, however, a 2010-2011 60 episode drama about Geunchogo’s life, which incorporates the Continental Baekje theories into its plot.
(As a quick aside, the Japanese and Korean historical texts get into a rather silly argument about which country was stronger. About whether Baekje sent those gifts to the Yamato court as a show of submission, or whether the Yamato court asked Baekje for help. It would seem a bit odd that a supposedly more powerful Yamato would be importing culture from a subservient country and not vice-versa. But for the most part, the two countries seemed to be on equal terms, and the arguments are on political rather than scholarly grounds.)