What is "youzhou"

Youzhou or You Prefecture (also known as You Province) is a place name for an ancient zhou or prefecture in northern China. Youzhou is cited in some ancient sources as one of the nine or twelve original provinces of China during early Chinese antiquity (22nd Century BC), but Youzhou was used in actual administration from 106 BC to the 10th Century AD. A prefecture as a political subdivision in Chinese history was at various times either the size of a province or sub-provincial unit known as commandery.

Youzhou was created in 106 BC as a province-sized prefecture during the Western Han Dynasty to administer a large swath of the dynasty's northern frontier that stretched from modern-day Shanxi Province in the west and Shandong Province in the south, through northeastern Hebei Province, southern Liaoning Province and southern Inner Mongolia to Korea. The prefectural capital was the City of Ji in modern Beijing. This prefecture continued to be centered in northern Hebei through the Three Kingdoms and Western Jin Dynasty.

In the Sixteen Kingdoms period, several of the kingdoms that ruled northern China used Youzhou to name commandery-sized prefectures in their domain. When northern China was unified under a single sovereign during the Northern Dynasties, Youzhou became a commandery-sized prefecture based in modern Beijing. During the Sui Dynasty, prefecture as a level of administration was not used and Youzhou was renamed Zhuojun or the Zhuo Commandery. Youzhou was revived during the Tang Dynasty as a smaller, commandery prefecture and became synonymous with the city that was Beijing during that era. In the Five Dynasties period, Youzhou was one of Sixteen Prefectures ceded to the Khitans of Manchuria. Thereafter, the name Youzhou was no longer used.

Three Kingdoms period
(In the late Han Dynasty period, 189 CE).