The Maritime-Historical Significance of Changes in the Paekche-Wa Sea Routes in the Sixth Century — Focusing on the “Daesa” and “Dasajin” Records in the Nihon Shoki during the Keitai Reign —

This study explores the shifts in the Paekche-Wa sea routes and the reorganization of maritime networks in the sixth century, focusing on the “Daesa” and “Dasajin” records in the Nihon Shoki during the reign of Emperor Keitai. Previous scholarship has generally viewed Paekche’s expansion into the eastern coastal region of Chŏllanam-do and the Sŏmjin River basin as an effort to secure a direct maritime route to Wa. In contrast, this study distinguishes the “Daesa” and “Dasa” records in the Nihon Shoki as stemming from different textual traditions, interpreting “Daesa” as a broad toponym encompassing the Hadong area, while “Dasajin” likely referred to a port situated near the Sŏmjin River estuary and the southern coast of Hadong. Paekche showed a keen interest in Kimun (present-day Namwŏn), a strategic inland transportation hub, and advanced toward the “Daesa” area at the lower Sŏmjin River to enhance regional stability. Conversely, the Koryŏng Kara-guk, a constituent polity of Kaya, regarded Hadong as significant for its direct access to the southern coastal routes. It is thus likely that Paekche focused on “Dasajin” within the “Daesa” region not as a primary stopover on the Paekche-Wa route but as a measure to check Koryŏng Kara-guk’s regional influence. The actual key port of call along the route seems to have been the Mijo-man area in southeastern Namhae Island, closer to the open sea than Hadong, which continued to appear in records after the Keitai period. The sixth century marked a period when Paekche expanded from the eastern coastal region of Chŏllanam-do into the Sŏmjin River basin, while the fall of the newly risen Koryŏng Kara-guk to Shilla led to the collapse of a pluralistic regional order. As both Paekche and Shilla moved toward centralized ancient state, the changes in the Paekche-Wa sea routes reveal a transitional phase in which the earlier long-distance coastal navigation network—with multiple ports of call—was reorganized into a new coastal route system centered on ports directly controlled by emerging centralized states.