Cao Jun's pinyin is cáo jūn Cao Jun. During the Three Kingdoms period, it refers to Cao Cao's army. After the establishment of Wei State, Cao Bing was renamed Wei Jun

Wei State (December 11, 22-February 8, 266) was one of the separatist regimes in the Three Kingdoms period, and later historians often called it Cao Wei. Since the later Northern Wei was called the "post-Wei", Cao Wei was also called the "pre-Wei" or "pre-Wei", which was the most powerful country in the Three Kingdoms.

In the last years of the Eastern Han Dynasty, there was chaos in the world, and competing with each other. In the scuffle between warlords, Cao Cao's power gradually increased, and he controlled the imperial court of the Eastern Han Dynasty, which laid the foundation for the establishment of Cao Wei. When Cao Cao was granted the title of Wei Gong, he ruled Ye, where Wei Jun was located in the Eastern Han Dynasty. Therefore, Emperor Xian of Han Dynasty named him "Wei Gong" and "Wang Wei", so his son Cao Pi established the title of "Wei".

In the first year of Yankang (22 years), Cao Pi forced Emperor Xian of Han Dynasty to abdicate, officially replaced the Han Dynasty, established Cao Wei, and made Luoyang its capital. By December of the second year of Emperor Xianxi (265 years), Bingyin (February 8, 266), Sima Yan usurped Wei, changed his title to Jin, and Cao Wei perished.

Because Cao Wei occupied the Central Plains in the Three Kingdoms, its national strength was far superior to that of Shu Han and Dongwu. During the Cao and Wei Dynasties, the most important reform was Chen Qun's Nine-grade Zhengzhi system, which had a far-reaching influence on the politics of the Jin and Southern and Northern Dynasties. In the territory, it inherited the rule of the Eastern Han Dynasty in the Western Regions, and established the Western Region Chief Historic Office to manage it. After Wu Qiujian conquered Goguryeo, the northern part of the Korean Peninsula was incorporated into the territory, and the southern States extended the Qinling Huaihe River to the borders of Shu and Wu.