Founding

According to chapter 45 of the Records of the Grand Historian, the royal family of Han was a cadet branch of the royal family of the state of Jin. The founder of the Han clan Wuzi of Han was the uncle of Duke Wu of Jin.^[7]

Members of the family became ministers in the powerful state of Jin and were granted Hanyuan (modern Hancheng in Shaanxi).

Spring and Autumn period

During the Spring and Autumn period, members of the Han family slowly gained more and more influence and power within Jin.^[2] In 453 BC, Jing of Han, along with Wen of Wei and Lie of Zhao partitioned Jin among themselves. In Chinese history, this Partition of Jin is the event which marks the end of the Spring and Autumn period and the beginning of the Warring States. Subsequently, Han was an independent polity. King Lie eventually recognized the new states in 403 BC^[2] and elevated the rulers to 侯 (hou, "marquess").

Warring States Period

In 375 Han defeated the neighboring state of Zheng (founded in 806 by the Zhou dynasty). Han conquered and annexed Zheng, thus expanding its territory. Han also moved its capital there, and assimilated Zheng's heritage. This included that of the young politician Shen Buhai (400-337).^[8][9]

Han's highest point occurred under the rule of Marquess Xi. Xi appointed Shen Buhai as his chancellor and implemented his Legalist policies. These reforms improved state administration and strengthened its military capability. Under King Xuanhui (r.  332–312 BC), Han declared itself an independent kingdom.

However, Han was disadvantaged in the competition of the Warring States period because Jin's partition had left it surrounded on all sides by strong states: Chu to the south, Qi to the east,^{[dubious – discuss]} Qin to the west, and Wei to the north. Han was then the smallest of the seven states and was without any easy way to further expand its own territory and resources, It was bullied militarily by its more powerful neighbors.

Defeat

During its steady decline, Han eventually lost the power to defend its territory and had to request military assistance from other states. The contest between Wei and Qi over control of Han resulted in the Battle of Maling, which established Qi as the pre-eminent state in the east. In 260 BC, Qin's invasion of Han led to Zhao intervention and the Battle of Changping.

During the late years of the era, in an attempt to drain Qin's resources in an expensive public works project, the state of Han sent the civil engineer Zheng Guo to Qin to persuade them to build a canal. The scheme, while expensive, backfired spectacularly when it was eventually completed: the irrigation abilities of the new Zhengguo Canal far outweighed its cost and gave Qin the agricultural and economic means to dominate the other six states. Han was the first to fall, in 230 BC.

In 226 BC, former nobility of the Han launched a failed rebellion in former capital Xinzheng, and King An, the last king of Han, was put to death the same year.

Han Xin was made a "Prince" or "King of Han" (韓王) by Liu Bang after the establishment of the Han dynasty (漢朝). He was removed to Taiyuan Commandery and the territory of the kingdom of Dai, where he defected to the Xiongnu and led raids against the Han Dynasty until his death.