King Chaekye, the ninth monarch of the Baekje Dynasty, came to the throne in the year 286 when his father, King Goi, died. Historical records say that he was well-built and ambitious. He married Lady Bogwa, the daughter of Daifang’s governor, to strengthen the alliance between his kingdom and Daifang. This area was the Chinese commandery and was situated in today’s Shandong Province in eastern China. It is believed that this is the first case of international marriage in the Baekje royal family. It shows Baekje exerted significant power over the tribe on the Chinese continent. But the marital alliance upset the northern kingdom of Goguryeo, which attacked Daifang in 286. King Chaekgye sent troops to help his wife’s country fend off the enemy. As the relations with Goguryeo worsened, the king fixed up two mountain castles located in present-day eastern Seoul to defend the Han River valley from possible invasions of Goguryeo.

Upon the invasion of Lelang, another Chinese commandery on the Shandong Province, in the year 298, the king led his army into battle himself and successfully stopped the enemy from advancing to his kingdom. Unfortunately, the king died in battle. Some historians say that some part of the Shandong Province was dominated by Baekje at the time, and the king went all the way to the Chinese continent to defend his territory. The historians claim that the king died there, not in the Baekje territory on the Korean Peninsula.

His son, King Bunseo, succeeded to the throne. He inherited his father’s hostility toward Lelang as well. Bunseo was described as being smart and having a commanding presence from an early age. He is said to have been adored by his father. He decided to take revenge on Lelang, as his father was killed during the battle against the Chinese commandery. Those who claim Baekje’s dominance over the commanderies on the Shandong Province also say that this king stayed in the Chinese continent to expand his territory. In 304, he took over the western region of Lelang in a surprise attack. In the same year, however, he died at the hands of an assassin sent by Lelang. In the end two kings of Baekje were killed by Lelang.

Clearly, the death of two Kings dealt a fatal blow to Baekje’s campaign to expand its territory into the Chinese continent. There are no records about battles against Lelang during the reigns of subsequent Baekje kings. Given this, it is assumed that Baekje’s policy to advance into the west, namely, the Chinese continent, weakened significantly after King Bunseo’s death. His name “Bunseo” means “divide the west.” It is speculated that he was deeply attached to the so-called “west Baekje” on the Chinese continent so much so that he even spent part his life there.