《 Sānguó zhì 》 zhōng chēng Liúbèi wéi xiānzhǔ, Liú Shàn wéi hòu zhǔ.
In the Records of the Three Kingdoms, Liu Bei is called the 'former ruler' and Liu Shan the 'latter ruler'.
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history
Most famously paired in Chen Shou’s 三国志: 刘备 is 先主, and his son 刘禅 is 后主. The pairing implies a small, short-lived state; only Shu Han (蜀汉) gets the 先主 / 后主 framing because there were just two rulers.