successor and younger brother of Taizu. He had a keen interest in the Southern Tang, whose final ruler Li Yu had been dethroned at the beginning of 976. Southern Tang governmental documents remained unprocessed when Taizong ascended to the Song throne later that year. Li Yu was posthumously granted the title prince of Wu (吳王) by Taizong in 978. This was the same title once held by Li Ke, the supposed ancestor of the Southern Tang house. Taizong probably saw it possible to claim to be the legitimate successor of the Tang through transmission from Li Yu and the Southern Tang. The Jiangnan lu was drafted by Tang Yue (湯悅) and Xu Xuan, both prominent members of the former Southern Tang government, to further the goal of connecting Taizong to the Southern Tang. It likely didnot achieve more than a minor circulation. By the 980s Taizong was more firmly in power and the text its significance as a source for him to claim legitimacy. The Jiangnan lu has been lost besides several passages existing in largely hostile sources. Xu Xuan was criticized by various scholars of the era for incorrectly depicting events that occurred in the Southern Tang. The author of the Diaoji litan accused Xu Xuan of blaming other officials for his own ruinous policies. The Jiangbiao Zhi by Zheng Wenbao and the Jiangnan Bielu by Chen Pengnian both in a partisan manner to fix these supposed errors. Later historians like Wang Anshi and Ouyang Xiu likewise critiqued the Jiangnan lu. Hostility to Xu Xuan by other Song historians likely came from a combination of his social prominence and prior service to the Southern Tang. The Diaoji litan 釣磯立談 was composed by a private citizen of the Southern Tang after its conquest by the Song. In the work the author defended the legacy of the Southern Tang. The Tang-Song interregnum was conceived as a period where competing states potentially had a limited mandate of heaven. They called the Southern Tang a "peripheral hegemonic state" 偏霸. An account was given of the Southern Tang geopolitical position and its plans for unifying China. By utilizing this terminology and logic the author disputed the negative status given to the Southern Tang by Song historians. 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