In fall 445, responding to prophecies that "Wu" would destroy Wei, a Xiongnu man, Gai Wu, started an uprising against Northern Wei at Xingcheng (杏城, in modern Yan'an, Shaanxi), and he was quickly joined by a large number of other Xiongnu and Han people. Gai also submitted as a vassal to Liu Song, seeking Liu Song aid. Initial attempts by local officials to stamp out Gai's rebellion failed, and Gai became stronger and stronger, claiming the title of Prince of Tiantai. In spring 446, Emperor Taiwu personally attacked and defeated Gai's ally, the Han rebel Xue Yongzong (薛永宗), before facing Gai. Gai fled into the mountains, and Emperor Taiwu carried out harsh reprisals against those who had supported Gai, slaughtering them without mercy. After Emperor Taiwu reached Chang'an, he found a number of Buddhist temples with weapons in them, and he believed that the monks must be working with Gai, so he slaughtered the monks in Chang'an. Cui used this opportunity to encourage Emperor Taiwu to slaughter all monks throughout the empire and destroy the temples, statues, and sutras, and notwithstanding Kou's opposition, Emperor Taiwu proceeded to slaughter the monks in Chang'an, destroy the statues, and burn the sutras. He then issued an empire-wide prohibition of Buddhism. Crown Prince Huang, however, used delaying tactics in promulgating the edict, allowing Buddhists to flee or hide, but it was said that not a single Buddhist temple remained standing in Northern Wei. This was the first of the Three Disasters of Wu.