Introduction to the Jinglongquan Mansion Site on the Bohai Sea: The Bohai Kingdom was founded in 698 AD and died in 926 AD. In 755 AD, the capital of the King of Bohai moved from Helong City in Jilin Province (Xiande Prefecture in Zhongjing) to Bohai Town in Ning'an City (Longquan Prefecture in Shangjing). This was the first and largest administrative establishment in the history of Mudanjiang, and it became one of the famous metropolises in Northeast and Northeast Asia at that time. The Institute of Archeology of the Chinese Academy of Sciences (later affiliated to the Chinese Academy of Social Sciences) conducted large-scale exploration and excavation of the site from 1963 to 1964, further elucidating the shape and layout of the capital.