The historiographical term "Eighteen Kingdoms" (Chinese: 十八國), also translated as "Eighteen States", refers to the eighteen fengjian states in China created by military leader Xiang Yu in 206 BCE, after the collapse of the Qin dynasty. The establishment and abolishment of the Eighteen Kingdoms marked the beginning and end of a turbulent interregnum known as the Chu–Han Contention.
The details of the feudal division are as follows:
Xiang Yu (c. 232 – c. January 202 BC), born Xiang Ji, was a Chinese warlord who founded and led the short-lived kingdom-state of Western Chu during the interregnum period between the Qin and Han dynasties known as the Chu–Han Contention (206–202 BC). A nobleman of the former state of Chu, Xiang Yu rebelled against the Qin dynasty under the command of his uncle Xiang Liang, and was granted the title of "Duke of Lu" (魯公) by King Huai II of the restoring Chu state in 208 BC. The following year, he led an outnumbered Chu army to victory at the Battle of Julu against the Qin armies led by Zhang Han. After the fall of Qin, Xiang Yu divided the country into a federacy of Eighteen Kingdoms, among which he was self-titled as the "Hegemon-King of Western Chu" (西楚霸王) and ruled a vast region spanning central and eastern China, with Pengcheng as his capital.
Although a formidable warrior and tactician, Xiang Yu was poor in both diplomacy and strategy, especially after dismissing his own adviser Fan Zeng. He was later outcompeted by his main rival Liu Bang during the massive civil war among the rebel kingdoms, which concluded with his eventual defeat and suicide in a last stand at the Battle of Gaixia. The demise of Xiang Yu allowed Liu Bang to subsequently become the founding emperor of the newly established Han dynasty, which is widely regarded as a golden age in Chinese history.
The Chu–Han Contention (楚漢相爭), also known as the Chu–Han War (楚漢戰爭), was an interregnum of civil wars in Imperial China between the fall of the Qin dynasty in 206 BCE and the establishment of the Han dynasty in 202 BCE.
After the Qin dynasty was overthrown, the empire was divided into the Eighteen Kingdoms ruled by enfeoffed rebel leaders and surrendered Qin generals according to arrangement by Xiang Yu, the hegemon warlord. Due to dissatisfaction among the rebels, wars and rebellions soon broke out, most prominently between two major powers – Xiang Yu and Liu Bang, who were the rulers of the Western Chu and Han kingdoms, respectively. Other kingdoms also waged war against Chu and Han and among themselves, but these were largely insignificant compared to the Chu-Han conflict. The wars ended with a total victory to Liu Bang at the Battle of Gaixia, during which Xiang Yu committed suicide after losing all his men in a last stand. Having subdued all rival contenders, Liu Bang subsequently proclaimed himself emperor of the newly established Han dynasty.
Emperor Yi of Chu (died 206 BC), also known as King Huai II of Chu before receiving his de jure emperor title, personal name Xiong Xin, was the ruler of the revived Chu state during the final years of the Qin dynasty of China. In 209 BC, when rebellions broke out throughout China to overthrow the Qin dynasty, the Chu state, which had been previously conquered by the Qin state (precursor of the Qin dynasty) during the Warring States period, was revived as an insurgent state against Qin imperial rule. Xiong Xin, as a descendant of the Chu royal family and a grandson of King Huai of Chu, was found by Xiang Liang, who descended from a Chu noble family, and installed as the puppet ruler of the revived Chu state. After Xiang Liang was killed in battle in 208 BC, Xiong Xin attempted to assert his authority through Song Yi, whom he put in charge of Chu's armed forces. However, in the following year, Xiang Liang's nephew Xiang Yu launched a coup against Song Yi and seized power, making Xiong Xin a figurehead once more. In 206 BC, the rebels overthrew the Qin dynasty, after which Xiang Yu, who had emerged as the de facto leader of all the rebel groups, divided the former Qin Empire into the Eighteen Kingdoms. He promoted Xiong Xin to a more honourable title – Emperor Yi of Chu – and made him the nominal sovereign ruler over all the Eighteen Kingdoms. Xiang Yu then had Emperor Yi relocated to Chen County (郴縣; present-day Chenzhou, Hunan) and secretly ordered Ying Bu to assassinate the emperor.
Zhang Han (died c. June or July 205 BC) was a Chinese military general of the Qin dynasty. Between 209 and 208 BC, when uprisings against the Qin dynasty broke out, Zhang Han, along with Sima Xin and Dong Yi, led Qin forces into battle against the various rebel groups and defeated some of them. However, they lost to rebel forces led by Xiang Yu in 207 BC at the Battle of Julu and were forced to surrender. After the rebels overthrew the Qin dynasty in 206 BC, China was divided into the Eighteen Kingdoms and the three surrendered Qin generals were made kings – Zhang Han as the King of Yong, Sima Xin as the King of Sai, and Dong Yi as the King of Di. Their three kingdoms were collectively known as the Three Qins since they occupied the Guanzhong region, the heartland of the Qin state during the Warring States period. In 205 BC, Liu Bang, the King of Han, invaded Zhang Han's kingdom and defeated Zhang Han in battle. Zhang Han committed suicide after his defeat.