A 1423 Thai account of a mission to Sri Lanka mentions eight Khmer monks who again brought orthodox Mahavihara sect of Singhalese order to Kampuchea. This particular event belied, however, the profound societal shift that was taking place from priestly class structure to a village-based monastic system in Theravada lands. While adhering to the monastic discipline, monks developed their wats, or temple-monasteries, not only into moral religious but also education, social-service, and cultural centers for the people. Wats became the main source of learning and popular education. Early western explorers, settlers, and missionaries reported widespread literacy among the male populations of Burma, Thailand, Kampuchea, Laos, and Vietnam. Until the 19th century, literacy rates exceeded those of Europe in most if not all Theravada lands. In Kampuchea, Buddhism became the transmitter of Khmer language and culture." The Theravada revolution was therefore a grassroots movement of the Khmer people rejecting some of the oppressive practices of the god-king religion of Hinduism and Mahayana Buddhism. With the rise of Siam in the west and Vietnam in the east, the classical Angkor empire disappeared and the beginning of present-day Cambodia began. The center of government began to migrate away from Angkor to a more central location in the center of Cambodia, in the regions near present-day Phnom Penh. Cambodia became from this time forward a Theravada Buddhist nation. "Theravada Buddhism, unlike almost all the previous religions of the country, its doctrines were not imposed from above but were preached to the people. It was simple, required no expensive priesthood or temples and little ceremonial. Its missionaries practiced austerity, solitude, humility, and poverty. Their example and their direct contact with the people started to undermine the old state religion and the monastery which rested upon it. Theravada Buddhism remained the great belief and comfort of the Khmer people until 1975." Zhou Daguan, a Chinese visitor to the Royal Court of Cambodia at this time wrote of the presence of Theravada Buddhist monks in the latter days of Angkor. Zhou Daguan was an emissary from the court of Timur Khan, Emperor of China. Daguan lived in Angkor Thom for one year 1296-7 and wrote a small book about his observations in which he described Theravada monks with shaved heads, yellow robes and one shoulder bare, walking barefoot throughout Cambodia.