Letters, art and pageantry made the Court of Hsüan Tsung brilliant, but the splendour faded and his reign ended tragically in disaster and rebellion. The T'ang dynasty seemed in danger of collapse. But it emerged successfully from these troubles and continued for a century and a half. During the whole of this period the Emperors with one exception[655] were favourable to Buddhism, and the latter half of the eighth century marks in Buddhist history an epoch of increased popularity among the masses but also the spread of ritual and doctrinal corruption, for it is in these years that its connection with ceremonies for the repose and honour of the dead became more intimate. These middle and later T'ang Emperors were not exclusive Buddhists. According to the severe judgment of their own officials, they were inclined to unworthy and outlandish superstitions. Many of them were under the influence of eunuchs, magicians and soothsayers, and many of those who were not assassinated died from taking the Taoist medicine called Elixir of Immortality. Yet it was not a period of decadence and dementia. It was for China the age of Augustus, not of Heliogabalus. Art and literature flourished and against Han-Yü, the brilliant adversary of Buddhism, may be set Liu Tsung Yüan[656], a writer of at least equal genius who found in it his inspiration. A noble school of painting grew up in the Buddhist monasteries and in a long line of artists may be mentioned the great name of Wu Tao-tzŭ, whose religious pictures such as Kuan-yin, Purgatory and the death of the Buddha obtained for him a fame which is still living. Among the streams which watered this paradise of art and letters should doubtless be counted the growing importance of Central and Western Asia in Chinese policy and the consequent influx of their ideas. In the mid T'ang period Manichæism, Nestorianism and Zoroastrianism all were prevalent in China. The first was the religion of the Uigurs. So long as the Chinese had to keep on good terms with this tribe Manichæism was respected, but when they were defeated by the Kirghiz and became unimportant, it was abruptly suppressed (843). In this period, too, Tibet became of great importance for the Chinese. Their object was to keep open the passes leading to Ferghana and India. But the Tibetans sometimes combined with the Arabs, who had conquered Turkestan, to close them and in 763 they actually sacked Chang An. China endeavoured to defend herself by making treaties with the Indian border states, but in 175 the Arabs inflicted a disastrous defeat on her troops. A treaty of peace was subsequently made with Tibet[657].