Xi () was a Chinese vassal state during the Shang and Zhou dynasties and the Spring and Autumn period (1600 â 475 BCE) ruled by members of the Jë family (姬). Sometime between 680 and 684 BCE Xi was annexed by the State of Chu and ceased to exist as an independent state.
In 712 BCE the State of Xi sent a punitive expedition against the State of Zhèng. At that time, Duke Zhuang of Zheng had for many years repeatedly attacked large States such as Song and Wey amongst others and Zhèng was at the height of its military power. The expedition resulted in decisive defeat for Xi, and the Zuo Zhuan commentary on the expedition criticises Xi's overestimation of its own strength. Nonetheless, some scholars believe that Xi's expedition indicated its military was quite powerful and a match for Zheng.
In 684 BCE, Duke Ai of Cai was rude to Xë Guë, wife of the Duke of Xë. As a result, the Duke of Xë asked the State of Chà  to feign an attack on his own country so that when the State of Cài came to the rescue, Chà  could strike the State of Cài and humiliate Duke Ai of Cài. King Wen of Chu agreed, attacked Cài and his army captured the Duke.
Although he harboured a deep grudge, in front of King Wen, Duke Ai praised Xë Guë's beauty. Consequently, King Wén overthrew the State of Xë and married Xë Guë. The two sons she bore subsequently became the Chà  kings Du Ao and King Cheng of Chu. King Wén of Chà  doted on Xë Guë and in 680 BCE, at her behest, overthrew the State of Cài. King Wen subsequently set up the counties of Shen and Xi in the areas of the former eponymous states.
During the State of ChÃÂ's struggle for hegemony in the Spring and Autumn period, Xi County played an important role. At the Battle of Chengpu, ChàPrime minister Cheng Dechen did not lead the main Chàarmy but a smaller force composed primarily of troops from the counties of ShÃÂn and Xë. As a result, Chéng Déchén lost the battle whereupon King Chéng of Chà  said âÂÂâÂÂIf you return home, what would the bereaved elders of Xi and Shen do?âÂÂâÂÂ
In 585 BCE, the State of Jìn attacked the State of Cài. Chàsent troops from ShÃÂn and Xë to assist Cài. The high-ranking military leaders of Jìn knew that if they won this battle it would only mean the defeat of ShÃÂn and Xë counties, not the entire State of ChÃÂ, but that if they lost it would be a major humiliation, so the army decided to retreat. Gu Jiegang points out that since the two counties of ShÃÂn and Xë had enough troops and were sufficiently powerful to deal with the State of Jin's army, it is clear that the counties were both rich and populous.