Just as Islam spread from the Middle East to Inner Asia and from Afghanistan to India, in the late thirteenth, fourteenth, and fifteenth centuries it spread from various parts of India and Arabia to the Malay Peninsula and the Indonesian archipelago. Whereas the history of Islamic societies in other parts of Asia can be told in terms of empires and contiguous geographical areas, maritime Southeast Asia is a region of scattered peninsulas and islands. The sea was the connection among them. The region held a central position on the trade routes that connected China to the Indian Ocean, the Persian Gulf, and the Red Sea. The population of the region included not only local peoples but Chinese, Indians from Gujarat, and Arabs from Hadramawt. Hadramawtis were especially active as teachers, traders, judges, and officials and married and sired children with local women.

Whereas in other regions Islam was established by Arab or Turkish conquests, it was introduced into Southeast Asia by traveling merchants and Sufis, often coming from Arabia and western India. Whereas in the Middle East and India, Muslim regimes were founded by new political elites, in Southeast Asia existing regimes were consolidated by conversion to Islam. The continuity of elites gave strong expression to the pre-Islamic components of Southeast Asian–Islamic civilization. The royal culture of Java seems more local and less Muslim than the corresponding royal culture of the Mughal Empire was Indian. At the same time there were Muslim merchant communities typical of international Islam and also syncretisms of Islam and village cultures. Whereas Muslims remained a minority in India, in Indonesia and Malaya they became the overwhelming majority.