Sunni Islam's primary institution of authority, the caliphate, manifested in various regions of the Islamic Empire, and in several competing ways, throughout its early centuries. The spread of Islam to Southeast Asia, however, presents an interesting case of the diffusion of Islam by processes of cultural diffusion, including trade, music, and the fusing of local culture with new Islamic practices.
More than half of the world's Muslims live in Asia. One-third of them live in South Asia alone, primarily in Indonesia. In fact, the majority of the Muslim world has been in Asia since the 1st century of Islamic history. The origins of Islam in modern-day Saudi Arabia and the contemporary political focus on the Middle East, especially from the perspective of the United States and western Europe, tends to obscure the enormous role of Asian Islam in the global Muslim community.
India, Pakistan, and Bangladesh have large Muslim populations. Muslims also constitute a majority of the population in Malaysia, Brunei, Uzbekistan, Tajikistan, Kyrgyzstan, and Turkmenistan. There are large numbers of Muslims, though they are not a majority, in Kazakhstan, the Philippines, Thailand, Sri Lanka, Myanmar, Singapore, and China.
The spread of Islam to Asia was facilitated primarily by merchants rather than conquerors. By the end of the 17th century, Islam had spread throughout Southeast Asia. The vast ethnic, geographical, and religious diversity of this broad region occasioned an array of Islamic hybridizations with existing religious traditions, including Buddhism and Hinduism. It has become somewhat controversial, if academically questionable, to refer to Islam in Asia as "syncretic" or to consider that there is an Islamic "overlay" on other traditions. The adaptability of Islamic law and practice to local culture was and remains, however, a factor in its rapid diffusion throughout the world. Yet the blending of cultures is not so much an issue of borrowing elements of one religion to graft them onto another, but of innovation and ingenuity in the application and adaptation of material, textual, and aesthetic culture in the hands of each generation of historical actions. This is especially evident in the Islamic culture of Asia.
Though there are significant Shi‘i populations in Afghanistan and Pakistan, the vast majority of Asia's Muslims are Sunni. According to Tanya Storch, "most of the great Muslim missionaries to Southeast Asia were Sufi mystics of the Sunni sect." By the 13th century, Indian Sufis were among those highly engaged in the spread of Islam. Scholars often conclude that the rapid acceptance of Islam, by rulers and large numbers of people alike, was greatly eased by the fact that it was this more mystical denomination of Islam that arrived in the region. The relative diversity of practice and openness to varied aesthetic and musical expressions common in Sufism may have aided in making the relationship between Islam and other religions, especially Hinduism and Buddhism, slightly easier, especially in the north of India. This is not to say that "nothing changed on the ground" once people were exposed to and began embracing Islam, but that in general, conversion to Islam was not immediately or necessarily seen as a matter of making a great break with the traditions and cultures of the past. While there are certainly exceptions to this general characterization, it has been the case that Sufism itself, being marginalized from the mainstream Sunni majority, lends itself more easily to local and regional practices.
In the modern period, however, the hybridization of local culture and religion and Islamic belief is more complicated, especially in South Asia. While the vast majority of Sunnis in, for example, Pakistan or Indonesia exhibit a long-standing religious and cultural diversity, more traditional Islamic revivalists in the region have begun, in recent years, to be more heavily influenced by the Saudi-based brand of modern Islam called Wahhabism. This vocal minority of the population has seen resurgence in recent years, in spite of the fact that most people in the region find the austere, restrictive, and demanding tenets of Wahhabism at odds with the broader tradition of Islamic intellectual and traditional diversity from earlier periods.
It is important to draw a distinction between revivalists, however, and Islamists. The former tend to be concerned with religious change for its own sake, with a "return" to religious values without any overt or state agenda. The latter seek to mobilize religious change in efforts to affect state action or to transform a state. It could be said that Islamists look back in history for a "golden age" from which to draw models for personal and political behavior, whereas revivalists seek ways to devise and implement a new vision for the future.