Sanggyeong Yongcheonbu (Hangul: 상경용천부) or Shangjing Longquanfu, also known as Sanggyeong (상경, 上京) or Shangjing, Holhan Fortress (홀한성, 忽汗城) or Dongjingcheng (东京城), was the capital city of Balhae in 756–785 and 793–926.
Balhae was founded at the Dongmo Mountain by Dae Jo-yeong. However, Balhae set up five capitals to rule its territories, and also transferred the main seat of the government several times because stabilizing and strengthening central rule over various ethnic tribes in its realm, which was expanded temporarily.
In 756, during the reign of King Mun, Sanggyeong was established as the permanent capital near Lake Jingpo in the south of today's Ning'an, Heilongjiang province, in Northeast China.
Sanggyeong had an outer fortress built squarely around two inner cities; the "Gungseong" (Palace city) which housed royal palace of Balhae and the "Hwangseong" (Imperial city), which contained the government organizations. The perimeter of its outer fortress measures approximately 17 kilometres (11 mi).