Emperor Ai of Tang
Li Zuo was born in 892, at the main palace at the Tang imperial capital Chang'an. His father Emperor Zhaozong was already emperor at that point, and he was Emperor Zhaozong's ninth son. His mother was Consort He, who had previously given birth to an older brother of his, Li Yu, Prince of De, who was Emperor Zhaozong's oldest son.
Tang campaign against the Eastern Turks
The Eastern Turkic Khaganate, which had been a vassal to Tang Dynasty's predecessor Sui Dynasty, had turned against Sui during the reign of Emperor Yang of Sui (r. 604-618) and subsequently, during Sui's breakup late in Emperor Yang's reign, had intervened in the process by supporting various claimants to the imperial title—including Tang's founder Emperor Gaozu, Xue Ju the Emperor of Qin, Liang Shidu the Emperor of Liang, Liu Wuzhou the Dingyang Khan, Gao Kaidao the Prince of Yan, Dou Jiande the Prince of Xia, and Liu Heita the Prince of Handong—playing them off against each other to try to make them subservient to the Eastern Turkic Khaganate. In 623, Liu Heita, the last major challenger to Tang rule, was captured and killed by Emperor Gaozu's crown prince Li Jiancheng, marking the reunification of China under Tang rule. The Eastern Turkic Khaganate, to which Emperor Gaozu still paid allegiance and tributes, began a campaign of routine pillaging incursions into Tang territory, effectively asserting authority over Tang territory in that manner, while continuing to protect Liang, who remained as the sole Chinese claimant of imperial authority against Tang, and also fostering the aspirations of Emperor Yang's young grandson Yang Zhengdao (楊政道), who was in the khaganate with his grandmother Empress Xiao and carried the title of Prince of Sui. The Turkic incursions were causing so many problems for the Tang that Emperor Gaozu considered burning the capital Chang'an to the ground and moving his seat to the modern southwestern Henan region, a proposal that was supported by Li Jiancheng, another son, Li Yuanji the Prince of Qi, and the chancellor Pei Ji, but vehemently opposed by Gaozu's son Li Shimin, the Prince of Qin. Due to Li Shimin's opposition (and guarantee that eventually he would be able to defeat the Eastern Turks), Emperor Gaozu abandoned the proposal.