Zizhi Tongjian
The Zizhi Tongjian is an authoritative historical text published in 1084 that remains an important source for Chinese historiography. Sima Guang oversaw and edited the compilation that covered 1,300 years of Chinese history. Leaders of the southern states that claimed the title of emperor were instead referred to as "ruler" (主). The final chapters of the Zizhi Tongjian deal with the Southern Tang. They provide significant amount of information about the state. Sima Guang opined that conquering the north was beyond the capabilities of the Southern Tang. Contemporary scholars have noted that the personal biases of Sima Guang at times removed a sense of objectivity in the text. The ideological stances of the Zizhi Tongjian greatly influenced subsequent Song historiography, and are still prominent in modern scholarship.