Xian, the T'ang capital and at that time the greatest city in all Asia, numbering 1 million inside its walls and another 1 million in the suburbs, welcomed tribute envoys, merchants, and devotees of religions from all parts of Asia and farther west. Not only was this the greatest period of Buddhism in Chinese history, but Islam, Manichaeism, Zoroastrianism, Judaism, and Nestorian Christianity all entered China. At the same time, with the advent of a recentralized empire, the fortunes of Confucianism rose: the civil service examinations reintroduced by the Sui were significantly expanded, and during the reign of the second T'ang emperor, T'ai-tsung (627-49), a wide range of Confucian scholarly projects was undertaken under imperial sponsorship. T'ang power and prestige reached a zenith during the reign of T'ang Hsuan-Tsung (712-56). Chinese lyric poetry reached a high point, and the world's first printed book was produced. Eventually, however, military victories gave way to defeat, notably at the hands of the Arabs in 751; and in 755 the revolt of An Lu-shan, a semibarbarian general in the T'ang employ, transferred considerable power from the central government to military governors in the provinces, dealing the dynasty a blow from which it never fully recovered. The persecution (841-45) of Buddhists was largely an effort to return revenues from tax-free temple lands to the state. The military governors who brought down the T'ang founded five short-lived regimes, which, in turn, were replaced by a new age of prosperity under the Sung (960-1279), the beginning of China's early modern age.