In the first month of 220, Cao Cao died and in the tenth month his son Cao Pi forced Emperor Xian to abdicate, thus ending the Han Dynasty. He named his state Wei and proclaimed himself emperor in Luoyang. In 221, Liu Bei declared himself emperor, in a bid to restore the fallen Han Dynasty. (His state is known in history as "Shu" or "Shu Han") In the same year, Wei bestowed on Sun Quan the title of King of Wu. A year later, Shu declared war on Wu and met the Wu armies at the Battle of Xiaoting (also known as Battle of Yiling). At Xiaoting, Liu Bei was disastrously defeated by Sun Quan's commander Lu Xun and forced to retreat back to Shu, where he died soon afterward. After the death of Liu Bei, Shu and Wu resumed friendly relations at the expense of Wei, thus stabilizing the tripartite configuration. In 222, Sun Quan renounced his recognition of Cao Pi's regime and, in 229, he declared himself emperor of Eastern Wu in Wuchang.

Dominion of the north completely belonged to Wei, whilst Shu occupied the southwest and Wu the central south and east. The external borders of the states were generally limited to the extent of Chinese civilization. For example, the political control of Shu on its southern frontier was limited by the Tai tribes of present-day Yunnan and Burma, known collectively as the "Nanman" (southern barbarians).