Warring States period
Partition of Jin (453–403 BC)

The rulers of Jin had steadily lost political powers since the middle of the 6th century BC to their nominally subordinate nobles and military commanders, a situation arising from the traditions of the Jin which forbade the enfeoffment of relatives of the ducal house. This allowed other clans to gain fiefs and military authority, and decades of internecine struggle led to the establishment of four major families, the Han, Zhao, Wei and Zhi.

The Battle of Jinyang saw the allied Han, Zhao and Wei destroy the Zhi family (453 BC) and their lands were distributed among them. With this, they became the "de facto" rulers of most of Jin's territory, though this situation would not be officially recognised until half a century later. The Jin division created a political vacuum that enabled during the first 50 years expansion of Chu and Yue northward and Qi southward. Qin increased its control of the local tribes and began its expansion southwest to Sichuan.
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