Sanggyeongseong Palace and Nearby Balhae Remains
Balhae was founded in 698 and was ruled by 15 kings until it was destroyed by the Kitan invasion in 926. Among them, the founder King Go, the second King Mu, and the third King Mun, laid the foundation for the establishment of Balhae. Following King Mu's territorial expansion, Balhae organized central and local administrative organizations one by one, including five capitals, 15 prefectures, and 62 counties, for efficient governance and management of the expanded areas during the reign of King Mun. The five capitals were Donggyeong (East Capital), Seogyeong (West Capital), Junggyeong (Central Capital), Namgyeong (South Capital), and Sanggyeong (Upper Capital). King Mun moved the capital from Junggyeong to Sanggyeong to keep pace with the status of Balhae, which was growing in strength. Afterward, Donggyeong served as the capital temporarily, but Sanggyeong was the largest capital city of Balhae until its collapse. Come to think of it, Sanggyeong is the northernmost capital among the capitals of Balhae and also among the capitals of countries founded throughout Korean history.
Kim Eun-gook, Honorary Researcher