Xiang Yu in the context of "Emperor Yi of Chu"

Emperor Gaozu of Han (256 or 247 – 1 June 195 BC), personal name Liu Bang, was the founder and first emperor of the Han dynasty.

Liu Bang was among the few dynastic founders to have been born in a peasant family. He initially entered the Qin dynasty bureaucracy as a minor law enforcement officer in his hometown in Pei County, within the conquered state of Chu. During the political chaos following the death of Qin Shi Huang, who had been the first emperor in Chinese history, Liu Bang renounced his civil service position and became a rebel leader, taking up arms against the Qin dynasty. He outmanoeuvred rival rebel leader Xiang Yu to invade the Qin heartland and forced the surrender of the Qin ruler Ziying in 206 BC.

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.

After Liu Bang defeated Xiang Yu and proclaimed himself emperor of the Han dynasty, he followed the practice of Xiang Yu and enfeoffed many generals, noblemen, and imperial relatives as kings (Chinese: 王; pinyin: wáng), the same title borne by the sovereigns of the Shang and Zhou dynasties and by the rulers of the Warring States. Each king had his own semi-autonomous kingdom. This was a departure from the policy of the Qin dynasty, which divided China into commanderies governed by non-hereditary governors.

The kings were divided into two groups: yìxìng wáng, literally "kings of different surnames", and tóngxìng wáng, literally "kings of the same surname", i.e., the imperial surname Liu. All of the initial kings were yixing wang, with many tongxing wang being created on former territories of removed yixing wang. The yixing wang represented an obvious threat to the Han empire, and Liu Bang and his successors suppressed them as quickly as was practical: they had disappeared by 157 BC. The tongxing wang were originally left to their own devices but, after the Rebellion of the Seven States in 154 BC, their independence was curtailed. Eventually they lost most of their autonomy. For this reason, the title is also translated as "prince" when referring to later kings of the dynasty, to reflect both their link to the ruling house and the vestigial nature of the former vassal kingdoms.

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:

The Battle of Gaixia, also known as The Last Stand at Wu River, was a battle of annihilation during Early Imperial China, fought between the forces of Han under Liu Bang and Western Chu under Xiang Yu in December 203 BC. It was the final major battle of the Chu-Han Contention, a civil war period following the collapse of the Qin dynasty, which finally ended when Xiang Yu committed suicide after making a last stand by the west bank of Yangtze River at Wujiang. The victorious Liu Bang would ascend to the throne a few months after the battle, declaring himself Emperor of the newly established Han dynasty.

Xiang Liang (項梁; died 208 BC) was a Chinese military leader who led a rebellion against the Qin dynasty between 209 and 208 BC. He is best known as an uncle of Xiang Yu, the rival of the Han dynasty's founding emperor Liu Bang during the Chu–Han Contention.