Youyun Sixteen States

The Sixteen Prefectures of Youyun, also known as the Sixteen Prefectures of Yanyun and the Sixteen Prefectures of Youji, are important strategic locations in Chinese history, specifically referring to the sixteen prefectures that Shi Jingtang, the founder of the Later Jin Dynasty, ceded to the Khitan (Liao Kingdom) in 938 AD during the Five Dynasties and Ten Kingdoms period. The scope roughly covers today's Beijing, Tianjin, and northern parts of Hebei and Shanxi. The sixteen prefectures can be divided into two major regions: Yanzhou and Yunzhou: the Yanzhou region includes You (now Beijing), Ji, Ying, Mo, Zhuo, Tan, and Shun; the Yunzhou region covers Yun (now Datong, Shanxi), Ru, Gui, Wu, Xin, Wei, Ying, Huan, and Shuo, with a vast territory and dangerous terrain. Its strategic value is extremely high. The Yanshan Mountains and the Great Wall Pass within the territory are the natural barriers for the Central Plains to resist the northern nomads. They are also a prosperous land where agriculture and animal husbandry intersect and an important horse-producing area. The cession of this move has a profound impact on the pattern of later generations. After the establishment of the Northern Song Dynasty, due to the loss of this barrier, the north was wide open and was threatened by the Liao and Jin for a long time. During the Northern Song Dynasty, it was recaptured by the Northern Expedition many times. After a brief recovery in 1123, it was quickly lost. It was not until the establishment of the Ming Dynasty in 1368 that Xu Da's Northern Expedition took it back. The cession of the Sixteenth Prefecture of Youyun directly led to the passive defense of the Song Dynasty and the increase in military expenditures. It indirectly laid the hidden danger of "Jingkang's Shame" and was an important reason for the "weakness" of the Song Dynasty. Shi Jingtang also left an eternal infamy for his willingness to be the "son emperor".