 Sima Qian in the Records of the Grand Historian, written from 109 to 91 BC explains that Shun, sovereign who relinquished power to Yu the Great, felt the domain in north was too vast and created three new prefectures including Youzhou from Yanzhou.The "Book of Han", completed in AD 111, also lists Youzhou as one of the Twelve Ancient Provinces.All of these texts described Youzhou as essentially equivalent to the State of Yan, one of the seven powers of the Warring States era.