(常州, roughly modern Changzhou, Jiangsu), then Yue Prefecture (越州, roughly modern Shaoxing, Zhejiang), then Xu Prefecture (許州, roughly modern Xuchang, Henan). During Emperor Ruizong's second reign In 710, Emperor Zhongzong died suddenly—a death that traditional historians believed to be a poisoning carried out by his wife Empress Wei and daughter Li Guo'er the Princess Anle so that Empress Wei, like Wu Zetian, could become "emperor" and Li Guo'er could become crown princess. For the time, however, Emperor Zhongzong's son by a concubine, Li Chongmao the Prince of Wen, became emperor (as Emperor Shang), with Empress Wei as empress dowager and regent. Less than a month later, a coup led by Emperor Zhongzong's sister Princess Taiping and Li Dan's son Li Longji the Prince of LInzi killed Empress Wei and Li Guo'er. Emperor Shang was deposed, and Li Dan, himself a former emperor, became emperor again (as Emperor Ruizong). Emperor Ruizong recalled Yao Yuanzhi, then serving as the prefect of Xu Prefecture, to the central government to serve as the minister of defense (now with the changed title of Bingbu Shangshu (兵部尚書)) and gave him the chancellor designation of Tong Zhongshu Menxia Sanpin (同中書門下三品). He and another chancellor, Song Jing, were said to be concentrating on ending the problematic policies of Emperor Zhongzong's reign, including reforming the civil service system and removing officials who had improperly received offices by bribing powerful people at court. In particular, one abuse he and Song sought to reverse was how Emperor Zhongzong had commissioned several thousands of officials without review by the examination bureau (門下省, Menxia Sheng), which was in charge of reviewing imperial edicts, and at their requests, Emperor Ruizong removed these officials from their offices. (Because Emperor Zhongzong signified that a review by the examination bureau was not necessary by sealing the envelopes containing the commissions in a slanted manner, these officials were known as the "slanted-sealed officials" (斜封官).) Later that year, Yao was made Zhongshu Ling (中書令) – the head of the legislative bureau (now named Zhongshu Sheng (中書省)) and a post considered one for a chancellor. Meanwhile, Li Longji, while he was not Emperor Ruizong's oldest son or born of his wife, the deceased Empress Liu, was made crown prince after Emperor Ruizong's return to the throne because of his accomplishment in the coup against Empress Wei. He soon frequently clashed with his aunt Princess Taiping, however, on matters of politics,