Shangjing Longquanfu (Chinese: 上京龍泉府) or Sanggyeong Yongcheonbu (Hangul: 상경용천부), also known as Shangjing (上京) or Sanggyeong (상경, 上京), Huhan/Holhan Fortress (홀한성, 忽汗城), is an archaeological site in Ning'an, Heilongjiang, China. It was the capital of the Balhae (Bohai) Kingdom in 756–785 and 793–926.
The site is located in about 3 kilometres (1.9 mi) from the modern town of Dongjingcheng (东京城), and the ruined city is also colloquially called "Dongjingcheng". The site has been protected since the 1960s. The Chinese government has established the Bohai Shangjing National Archaeological Park and an archaeological museum at the site.
Shangjing was modelled after Chang'an, capital of the Chinese Tang dynasty. It was about one fifth of the size of Chang'an, measuring 4.68 kilometres (2.91 mi) from east to west, and 3.47 kilometres (2.16 mi) from north to south. It was composed of the outer city, the inner city, and the palace city which enclosed five palaces. It is one of the best preserved medieval capital cities in the world.
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, Shangjing Longquanfu was established as the permanent capital near Lake Jingpo, south of today's Ning'an, Heilongjiang, China.
- "渤海上京考古遗址公园（第二批国家考古遗址公园）" [Bohai Shangjing National Archaeological Park] (in Chinese). Institute of Archaeology, Chinese Academy of Social Sciences. 25 April 2014.
- (in Korean) "Sanggyeong Yongcheonbu", Naver encyclopedia