蜀国 / Shu State (Warring States)
蜀国 / Shu State enters the wiki through 《资治通鉴·周纪》52丨 陈庄叛秦 端起碗吃饭放下碗骂娘 as the polity 秦国 conquers after accepting 司马错’s advice. The episode says Shu and 巴国 are fighting and both seek Qin help, letting Qin turn an outside request into regional conquest.
After conquest, Qin lowers the former ruler to 蜀侯宁通 and appoints 陈庄 as chancellor. This arrangement preserves enough local form to govern, but it also creates the later rebellion when Chen Zhuang kills Ning Tong and tries to hold Shu for himself.
In the episode’s interpretation, Shu is not only hard terrain. It is also part of 巴蜀’s grain and resource base, especially once later irrigation such as 都江堰 makes the region supply Qin more powerfully.