The period from 220 AD to 589 AD witnessed the rise and fall of the Wei, Jin, Southern and Northern Dynasties in Chinese history.
A turbulent political situation, the rise of multiple hegemonies and the entry of northern ethnic groups into the central plains resulted in long-tem disunity of the country and confrontation between the south and north. The main reason for the struggles among local warlords was the malignant expansion of local despots since the Eastern Han Dynasty. That finally resulted in the rise of three powers, known as Caowei, Shuhan and Sunwu.
1 Cao Cao
Cao Cao was once the Commander for Military Standards during the regime of Emperor Lingdi at the end of the Han Dynasty and participated in the allied troop crusading against the rebellious minister Dong Zhuo. He later defeated the Yellow Turbans Uprising at Qingzhou, incorporated more than 300,000 soldiers and further established a valiant army called "Qingzhou Troops." In 196 AD, Cao Cao tookback Emperor Xiandi, who had been held under duress by Dong Zhuo, and moved the capital to Xuxian (present-day Xuchang, Henan), gaining a favorable position of "coercing the king to control all his vassals." In 200 AD, he won the battle at Guandu against the troops of Yuan Shao and gained control over areas both north and south of the Yellow River. Cao Cao further conquered Wuhuan of Liaoxi, basically unifying the northern part of China. In 208 AD, he led a troop southward but was defeated by the allied army of Sun Quan and Liu Bei at Chibi, resulting in the pattern of separatist regimes among three kingdoms. Retreating to the north, Cao Cao successively occupied Guanzhong and Liangzhou and expanded the scope of his power in the northwest areas. After Cao Cao's death in 220 AD, Cao Pi dethroned Emperor Xiandi and established the Wei Dynasty, which was historically called Caowei.
2 Liu Bei
Liu Bei was a descendant of the royal family of the Han Dynasty. After the family fortunes declined in his early years, he went to his relative, Liu Biao, the governor of Jinzhou, for help. As a man of ambition, Liu Bei always hoped for hegemony and went everywhere for talents who could assist him. It is said he once paid three visits to the thatched cottage in Longzhong, Jinzhou to invite Zhuge Liang, who had retreated for refuge. Following the death of Liu Biao, Liu Bei controlled Jinzhou. In 211 AD, he attacked Hanzhong and further occupied Yizhou in Sichuan, consolidating his rule over the southwestern regions. In 221 AD, Liu Bei declared himself a descendant of the former imperial family and established a state, historically called Shuhan, with the capital in Chengdu. Assisted by Prime Minister Zhuge Liang, Liu Bei implemented clean politics and paid particular attention to the state's relations with local ethnic groups. Economically, he also made a vigorous effort to popularize raising silkworms, and to develop iron-smelting, textile and other handicraft sectors, leading to the rapid development of the southwestern regions and close ties with the central plains.
3 Sun Quan
Relying on rich and powerful landlords and inheriting his family fortunes in areas south of the Yangtze, Sun Quan was confronted with Caowei across the Yangtze and energetically expanded in areas south of the river. He later eliminated the forces of Liu Bei from Jinzhou and occupied Lingnan, extending his scope of power southeastward. In 229 AD, Sun Quan ascended the throne, established Jianye (present-day Nanjing) as the capital and changed the state tile to Wu, which was historically called Sunwu. Sun Quan had outstanding achievements in developing the economy in the backward areas south of the Yangtze.
Wei, Shu and Wu each achieved a regional unification, respectively making significant contributions to local society.
Drastic social turmoil and long-term wars led to the division of the state, economic decline and destruction of social civilization. After more than three centuries of chaos, many northern ethnic groups gradually merged during the regime conflicts and exchanges. The southern areas made unprecedented economic development and laid a solid foundation for reunification at a higher level.