Kukai returned to Japan after Huiguo's death. If he had not, Shingon Esoteric Buddhism might not have survived; 35 years after Huiguo's death in the year 840, Emperor Wuzong of Tang assumed the throne. An avid Daoist, Wuzong despised Buddhism and considered the sangha useless tax-evaders. In 845, he ordered the destruction of 4600 vihara and 40,000 temples. Around 250,000 Buddhist monks and nuns had to give up their monastic lives. Wuzong stated that Buddhism was an alien religion and promoted Daoism zealously as the ethnic religion of the Han Chinese. Although Wuzong was soon assassinated by his own inner circle, the damage had been done. Chinese Buddhism, especially Esoteric practices, never fully recovered from the persecution, and esoteric elements were infused into other Buddhist sects and traditions.