This study examines the crucial policies in the governance of Baekje, a kingdom in the 5th century, with a focus on its response to the invasions by Goguryeo, a neighboring kingdom. King Biyu, who came from the moderate faction known as the clan “Hae” was established as the ruler, following a diplomatic approach of not provoking Goguryeo, which had been maintained since the reign of King Jeonji. However, a shift in Baekje's stance can be detected in the negotiation with the Southern Dynasties of China, particularly during the year 450.
 The negotiation with the Song Dynasty, mediated by Fungyabu, a North Korean envoy in the Northern Dynasties, aimed to undermine the relationship between Baekje and Goguryeo, while maximizing diplomatic gains for Baekje. Through negotiations with Song Dynasty in 450, Baekje sought to constrain Goguryeo and strengthen its own influence.
 Additionally, the items demanded by Baekje from the Song Dynasty, such as “Yeok-rim”, “Sikjeom”, and “Yono”, indicate the needs and policies of Baekje around 450. Yeok-rim and Sikjeom signify the introduction of new military tactics to expand Baekje's policy position, while Yono implies a focus on military reinforcement and weapons acquisition. The dispatch of Fungyabu and the requested items reflect a shift in Baekje's policy towards a more confrontational approach with Goguryeo, revealing the internal dynamics within Baekje.
 In September 455, immediately before his death, King Biyu is recorded to have encountered a “Black Dragon” in the “Han River” region. Notably, King Biyu went hunting in “Hansan” in March, a region that frequently appeared in the context of conflicts with Goguryeo. His hunting in Hansan was likely meant to assert his control over the military forces, emphasizing the imminent confrontation with Goguryeo. These actions by King Biyu contradicted the moderate policies pursued by the Haesei faction, which had previously dominated Baekje's approach towards Goguryeo, indicating potential friction between the moderate faction led by the clan “Hae” and the hardline faction led by King Biyu.
 Following King Biyu's death, a significant shift occurred within the moderate faction led by the clan “Hae”, leading to an internal conflict with the hardline faction led by King Gaero. Approximately a month after King Biyu's demise, in October 455, Goguryeo launched an invasion on Baekje, which was eventually repelled with the assistance of a Silla relief force. This event undermined the legitimacy of the moderate faction, including the clan “Hae”, in the succession dispute, ultimately resulting in King Gaero ascending the throne and the victory of the hardline faction.
 Indeed, the rise of King Gaero, who suppressed the moderate faction and seized power, and his supporting faction inherently faced limitations in adopting a tough stance against Goguryeo.
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