Religion and culture
New religions appeared in Southeast Asia, accompanying the currents of trade and often entwined with social changes already underway. Gradually, in most areas, these religions filled the gaps left by weakening local Hindu-Buddhist establishments and beliefs, and by the mid-18th century the region had assumed something much like its modern religious configuration. On the mainland, Theravāda Buddhism, which had been making inroads in Cambodia since the 11th century, underwent revitalization, the result especially of royal patronage and direct contact with Theravāda monasteries in Sri Lanka. Both the general idiom and many precepts of Theravāda already were familiar in Indianized societies, making this a gentle, nearly silent revolution that despite its subtlety was no less important. In Ayutthaya and the other Tai kingdoms and in the Mon-Burman states, Theravāda Buddhism buoyed the kingship and introduced a vigorous intellectual leadership; it also spread broadly among the populace and thus played an important role as a cohesive social and cultural force from which the people of modern Thailand and Myanmar later were to draw much of their sense of identity.
Christianity made its appearance in the early 16th century, brought by the Portuguese, Spanish, and, somewhat later, the French. It spread easily in the northern Philippines, where Spanish missionaries did not have to compete with an organized religious tradition and could count on the interested support of a government bent on colonization. Unlike the religions with which Southeast Asia had been familiar, Christianity showed no interest in syncretic accommodation of local animist or other beliefs. The Spanish friars rooted out whatever they could find in the way of indigenous tradition, destroying much of cultural value, including, it appears, a native writing system. By the 18th century, most of the Philippines, except the Muslim south, was Roman Catholic, and a society that was both Filipino and Christian had begun to evolve. Elsewhere in Southeast Asia, however—with the exception of Vietnam and parts of the Moluccas island group of eastern Indonesia—Christianity attracted little interest. It did not go unopposed and was resisted, for example, by Buddhist monks in Thailand and Cambodia in the 16th century, but Christian doctrines do not appear to have attracted the general populace. There were few conversions, and rulers were not unduly disturbed by the presence of missionaries, except on occasions when they were accompanied by political and economic adventurers; these people were crushed.
Islām, however, captured the imagination of Southeast Asians in the archipelago. It was proselytized primarily by Malacca and Aceh after 1400 and by the late 17th century was the dominant faith from the western tip of Sumatra to the Philippine island of Mindanao. The conversion process was gradual, for Muslim traders from the Middle East and India long had traveled the sea route to China; it seems likely that they traded and settled in the port cities of Sumatra and Java as early as the 9th or 10th century. Perhaps as a result of weakening of the Hindu-Buddhist courts and the rise of smaller, independently minded trading states and social classes, Islām made important inroads among both ruling elites and others.
Conversion was comparatively easy and promised certain practical advantages, especially in trade, to members of the Islāmic community (the ummah). In addition, Islām was itself diverse, offering a spectrum of approaches from mystical to fundamentalist, and in practice Muslim proselytizers often were tolerant of syncretic behaviour. In addition, Islāmic culture, especially poetry and philosophy, was particularly attractive to courts anxious to enhance their status as cultural hubs. While the spread of Islām throughout the archipelago was not entirely peaceful, for the most part it proceeded in evolutionary fashion and without remarkable disturbance. Javanese Muslims, perhaps even members of the court, lived peacefully in the capital of Hindu-Buddhist Majapahit, for example, and Muslims and non-Muslims everywhere continued to trade, enter into alliances, and inhabit the same general cultural world. What change there was tended to occur slowly in the face of robust and deeply rooted tradition. In some societies the cultural response was original and lively. Along the northern coast of Java, for example, architecture, batik cloth-dyeing motifs, and the literature and performance of the wayang (shadow-puppet theatre) were deeply affected by Islāmic ideas and produced vital new forms to accompany the old.