Baekje’s Regional Governance of the Yesan(禮山) Region and Yesansanseong Fortress(禮山山城)

In the restoration of history, understanding local regions along with the central government is a crucial element. However, the lack of historical sources related to local areas serves as an obstacle to a concrete understanding of them. Nevertheless, efforts to understand localities on a micro level are continuously necessary for reconstructing and comprehending specific aspects of history. With this awareness, this study examined how the Yesan region was utilized during the Baekje period. To this end, an analysis of the place names that have survived from the Baekje era, along with an examination of the Yesansanseong Fortress constructed during the same period, was conducted.<br/> The place names related to Yesan that appear in historical records such as the Samguk Sagi and the Nihon Shoki include Dugok, Mapojin, Hosan, Doksanseong Fortress, and Majin. The relocation of people from Dauseong Fortress to Dugok, as well as the hunting expeditions in the Yesan area during the reigns of Kings Dongseong and Muryeong, reflect the regional importance of this area. This significance becomes even more pronounced in the Battle of Doksanseong Fortress, which took place during the Sabi period. The Battle of Doksanseong Fortress was a major conflict that renewed the Baekje–Silla alliance, which had long remained in a state of tension, and resembled an international war in scale. Thus, Doksanseong Fortress—also known as Yesansanseong Fortress—symbolizes the strategic and historical importance of this region in Baekje history. In this way, the Yesan area served as a vital local stronghold during the Baekje period.<br/> In this way, Yesansanseong Fortress served as a major battlefield between Baekje and Goguryeo after Baekje relocated its capital to Ungjin. Consequently, Baekje inevitably regarded the northwestern area of present-day Chungcheongnam-do, with the Charyeong Mountain Range as the strategic dividing line, as a region of great military importance. This is clearly demonstrated by the establishment of the Seobangseong(Western Fortress) in the area around Imjonseong Fortress following the formation of the five-province administrative system. Naturally, with the establishment of the Western Fortress in the Imjonseong Fortress region, Yesansanseong Fortress came to perform multiple functions, serving both as the administrative stronghold of Osan-hyeon and as a defensive and surveillance base for the Western Fortress. As a result, the significance of Yesansanseong Fortress further increased. This is also supported by evidence of Baekje’s naval activities centered around the Muhancheon River. Thus, due to its geographical characteristics, Yesansanseong Fortress functioned as an important military stronghold in the northwestern region of Baekje. Moreover, during the Ungjin period, as the Taean Peninsula was newly developed as a maritime route to China, this region also drew attention as a key transportation corridor along that route.