of the last Tang emperors and ruled China during a long period of decline; despite his reforms, he was unable to revive the empire through his religious persecutions. After his death, with the help of his uncle Emperor Xuānzong, Buddhism was able to recover from the persecution; but Christianity, Manichaeism, and Zoroastrianism never again played as significant a role in Chinese religious life.) Dealing with the Huigu incursions By the time that Emperor Wuzong took the throne, his mother Consort Wei had already died, and he posthumously honored her as an empress dowager. Also, knowing that Yang Sifu and Li Jue had not supported him as Emperor Wenzong's successor, he had them removed from their offices. He instead installed Li Deyu, former chancellor under Wenzong, as a chancellor and effectively put most of the responsibilities of governance in his hands. (In 841, Emperor Wuzong further ordered Liu Hongyi and Xue Jileng to commit suicide and planned to order Yang and Li Jue to do so as well, but Yang and Li Jue were spared (and only demoted) after the intercession by Li Deyu and the other chancellors, Cui Gong, Cui Dan, and Chen Yixing.) One of the first things that Emperor Wuzong had to deal with was the collapse of Tang's erstwhile vassal and ally Huigu—which had supported Tang in various campaigns through the decades. In 840, due to internal power struggles, Huigu was weakened, such that when the Xiajiasi (Kirghiz) khan Are () attacked, the Huigu khan Yaoluoge Hesa () was killed. The Huigu tribespeople scattered, fleeing in various directions. One major group, under the leadership of the prince Wamosi and the nobles Chixin (), Pugu (), and Najiachuo (), headed for the Tang border city of Tiande (天德, in modern Hohhot, Inner Mongolia) and sought to submit to Tang. The leader of another major group, the noble Yaoluoge Wuxi, claimed the khan title for himself (as Wujie Khan). Wujie Khan subsequently seized Emperor Wuzong's aunt Princess Taihe, who had married a previous khan (Chongde Khan), and held her hostage. Various Huigu remnants pillaged the Tang border regions, causing much disturbance for the Tang people. At Li Deyu's suggestion, Emperor Wuzong supplied food to the Huigu remnants to try to calm them, while accepting Wamosi's submission. When Wujie Khan subsequently demanded that Tang turn Wamosi over to him as a traitor, Emperor Wuzong refused. Subsequently, Wujie Khan's forces and