Li Chengqian in the context of "Chancellor of the Tang dynasty"

Emperor Gaozong of Tang (21 July 628 – 27 December 683), personal name Li Zhi, was the third emperor of the Chinese Tang dynasty, ruling from 649 to 683; after January 665, he handed power over the empire to his second wife Empress Wu (the future Wu Zetian), and her decrees were carried out with greater force than the decrees of Emperor Gaozong's. Emperor Gaozong was the youngest son of Emperor Taizong and Empress Zhangsun; his elder brothers were Li Chengqian and Li Tai.

Emperor Gaozong's reign saw the primacy of Empress Wu, who became the effective power behind the Tang rule. Empress Wu aided Emperor Gaozong in his rule during the later years of his reign after a series of strokes left him incapacitated. Emperor Gaozong effectively after January 665 delegated all matters of state to Empress Wu; after that the empress acted as the power behind the emperor, "hanging the curtain and listening to politics" (垂簾聼政; Chuílián tīngzhèng). Gaozong's personal illness, affection and trust of Wu led to her wielding a great deal of power in affairs of state until the end of his reign. From official histories from the later Tang Dynasty to contemporary historians, there exists a lively debate about whether Wu exerted undue influence on Gaozong, or whether they were equal partners in the government. Empress Wu was partially in control of power from November 660 and then totally from January 665 to December 683; there was an equality of power between Gaozong and Wu, which caused them to be called "two saints" (二聖; Er Sheng, literally two emperors) both inside and outside. After Emperor Gaozong died in December 683, power fell completely and solely into the hands of Empress Wu, acting as Empress Dowager-regent, "presiding over court and issuing edicts" (臨朝稱制; lin chao chengzhi); she subsequently became the only empress regnant in Chinese history. After his death, he was interred at the Qian Mausoleum along with Wu Zetian.

Li Tai (Chinese: 李泰; pinyin: Lǐ Tài; 620 – 14 January 653), courtesy name Huibao (惠褒), nickname Qingque (青雀), formally Prince Gong of Pu (濮恭王), was an imperial prince of the Chinese Tang dynasty.

Li Tai, who carried the title of Prince of Wei (魏王; "Wei wang"), was favored by his father, Emperor Taizong, for his literary talent and studiousness. His older brother Li Chengqian was crown prince, but Li Tai and his associates had design on that position, eventually pushing Li Chengqian to plot treason in 643. After Li Chengqian's plot was discovered, Li Chengqian was deposed, and Emperor Taizong agreed to create Li Tai the new crown prince. However, Emperor Taizong soon saw that Li Tai had pushed Li Chengqian toward rebellion by machination and further appeared to bear ill intentions toward their younger brother Li Zhi the Prince of Jin, and so Emperor Taizong named Li Zhi crown prince instead. Li Tai was reduced in rank and briefly put under house arrest, and then exiled. He died in exile in 653.