The Three Kingdoms (220-280) was a period of history that began with the Eastern Han Dynasty and ended with the Western Jin Dynasty, and was divided into three regimes: Cao Wei, Shu Han, and Eastern Wu. At the Battle of Red Cliff, Cao Cao was defeated by the allied forces of Sun and Liu, setting the stage for the Three Kingdoms.
In 220, Cao Pi usurped the throne of Han and assumed the state name of Wei, which became known as Cao Wei, and the history of the Three Kingdoms officially began. In the following year, Liu Bei continued the Han Dynasty in Chengdu, which became known as Shu Han. 222, Liu Bei lost the Battle of Yiling, and Sun Quan gained most of Jingzhou. 223, Liu Bei died, and Zhuge Liang assisted Liu Bei's son, Liu Zen, to re-establish an alliance with Sun Quan. 229, Sun Quan became the emperor, and his country was named Wu, which became known as Eastern Wu, and the Three Kingdoms were formally established.
In the decades that followed, Zhu Geliang and Jiang Wei of Shu Han led many northern expeditions against Cao Wei, but they were unable to change the pattern of the Three Kingdoms. In 263, Sima Zhao of Cao Wei launched the battle of Wei against Shu, which led to the fall of Shu Han. Two years later, Sima Zhao died of illness, and his son Sima Yan abrogated Emperor Yuan of Wei and established a state called Jin, which was known as Western Jin. In 280 AD, the Western Jin Dynasty destroyed the Eastern Wu and unified China, thus ending the Three Kingdoms period and entering the Jin Dynasty.