It was located in present-day Hebei province as well as Beijing and Tianjin municipalities.
In western Han dynasty, the commandery administered 12 counties, including Yuyang, Hunu (狐奴), Lu (路), Yongnu (雍奴), Quanzhou (泉州), Pinggu (平谷), Anle (安樂), Tixi (厗奚), Guangping (獷平), Yaoyang (要陽), Baitan (白檀) and Huayan (滑鹽),[2] the last 3 of which were abolished during the eastern Han dynasty.
[3] In Jin dynasty, the commandery was abolished and its land were incorporated into the Principality of Yan (燕國).
It administered 6 counties, and the Book of Wei documented 6,984 households and a population of 29,670.
In Tang dynasty, Yuyang became an alternative name for Ji Prefecture (薊州).