Three Kingdoms
The legitimacy issue

Traditional Chinese political thought is concerned with the concept of the " Mandate of Heaven ", from which a ruler derives legitimacy to rule all under heaven. In the Three Kingdoms period, Cao Wei, Shu Han, and Eastern Wu all laid claim to the Mandate by virtue of their founders declaring themselves as emperors. Later historians would disagree on which of the Three Kingdoms (primarily between Wei and Shu) should be considered the sole legitimate successor to the Han dynasty.

Chen Shou, the compiler of the Records of the Three Kingdoms, hailed from Shu Han and became an official of the Western Jin dynasty when he was working on the Records. As Western Jin succeeded Cao Wei, Chen was careful in his compilation to imply Cao Wei was the legitimate state. Despite the description of events being mostly balanced and fair, Chen Shou legitimised Wei by placing the Wei annals first, using the era names from Wei's calendar, and reserving regal nomenclature for the leaders of Wei. Specifically, emperors of Cao Wei are referred to by their imperial posthumous names (e.g. Cao Pi is referred to as the "Civil Emperor" 文帝), while the Shu and Wu emperors are mere "rulers" (e.g. Liu Bei is referred to as the "First Ruler" 先主 and Sun Quan as "Ruler of Wu" 吳主). Chen Shou, as a subject of Jin, could not write in a way that implies Jin as illegitimate by denying Cao Wei's claim to the mandate, despite what sympathies he might have had toward his home state of Shu.

Chen Shou's treatment of the legitimacy issue was generally accepted through to the Northern Song dynasty. Despite maintaining that none of the three states truly held the Mandate of Heaven since they all failed to unify China, Song historian Sima Guang used Wei's era names and thus affirmed the legitimacy of Wei's succession to Han in his universal history Zizhi Tongjian. Sima Guang explained that his choice was merely out of convenience, and he was "not honouring one and treating another with contempt, nor making distinction between orthodox and intercalary positions." Nonetheless, the influential Neo-Confucian moralist Zhu Xi criticised Sima Guang's choice, taking the position that Shu Han was the true successor to the Han dynasty since Liu Bei was related to the imperial Liu clan by blood, and thus used Shu's calendar in his rewrite of Sima Guang's work, the Zizhi Tongjian Gangmu. This position, first argued by Xi Zuochi in the fourth century, found support in Zhu Xi's time since the Song dynasty found itself in a similar situation as Shu Han, as it was forced out of north China by the Jurchens in 1127 and became known as the Southern Song. The revisionist private histories of the time emphasised " humane governence" (仁政) as a mark of legitimate dynastic succession, and saw Liu Bei as an idealised Confucian monarch. The pro-Shu bias then found its way into popular forms of entertainment such as Sanguozhi Pinghua, a pinghua tale, and zaju performances, and was eventually codified in the 14th century historical novel Romance of the Three Kingdoms.
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