Youzhou was first instituted as an administrative unit in 106 BC during the Han Dynasty. In 106 BC, Emperor Wu of Han organized the Western Han Dynasty into 13 province-sized prefectures, each administered by a "cishi" () or inspector. You Prefecture comprised the Shanggu, Zhuo, Guangyang, Dai, Bohai, Yuyang, Right Beiping, Liaoxi, Liaodong, Xuantu and Lelang Commanderies. Altogether the eleven commanderies contained 173 counties. The prefectural seat was the City of Ji in Guangyang Commandery, which is part of modern Beijing Municipality. Youzhou was bordered by Bingzhou (present-day eastern and northern Shanxi) in the west, Jizhou (southern Hebei) and Qingzhou (northern Shandong) in the south, Korea in the east and the steppes in the north.