Islam is the most widely practised religion in Southeast Asia, numbering approximately 240 million adherents which translate to about 42% of the entire population, with majorities in Brunei, Indonesia and Malaysia as well parts of Southern Thailand and parts of Mindanao in the Philippines respectively. Significant minorities are located in the other Southeast Asian states. Most Muslims in Southeast Asia are Sunni and follow the Shafi`i school of fiqh, or religious law. It is the official religion in Malaysia and Brunei while it is one of the six official faiths in Indonesia.
Islam in Southeast Asia is heterogeneous and is manifested in many different ways. In some places in Southeast Asia, Islam is adapted to coexist with already existent local traditions. Mysticism is a defining characteristic of Islam in Southeast Asia, with a large following of Sufism. Mystic forms of Islam fit in well with already established traditions. The adaptation of Islam to local traditions is seen as a positive thing by Muslims in Southeast Asia. Islam is part of everyday life in Southeast Asia and is not separated from "non-religious realms". Southeast Asia contains the highest number of Muslims in the world, easily surpassing the Middle East and North Africa. Islam in Southeast Asia is neglected in Western study of Islam which centers around the Middle East.
Southeast Asian identity varies by regions that include Brunei, Cambodia, East Timor, Indonesia, Malaysia, Myanmar, the Philippines, Singapore, Thailand, and Vietnam. The heterogeneous nature of Southeast Asia combined with the widely varying practices and meanings of Islam suggests Islam in Southeast Asia has a multitude of variations in practice and belief. Islam in Southeast Asia has been adapted into varying local norms across Southeast Asia. The Abangan are the dominant group of Muslims in Indonesia. The practices of the Abangan are heavily influenced by mysticism and embody a unique form of Islamic practice that incorporates rituals inherited from their pre Islamic ancestors.
History
Muslim merchants dominated trade in Southeast Asia by the 9th century or earlier. There existed a colony of foreign Muslims on the west coast of Sumatra by 674 AD; other Muslim settlements began to appear after 878 AD when Islam increasingly took root among the people. However, little remains from these early communities, and the religion did not spread to significant parts of the population until the 12th century.
Muslim traders along the main trade-route between Western Asia and the Far East are thought to have been responsible for the introduction of Islam to Southeast and East Asia. The religion was then further spread by Sufi orders and finally consolidated by the expansion of the territories of converted rulers and their communities. The first Muslim communities arose in Aceh in Northern Sumatra. Malacca was an early stronghold of Islam as well, and it served as a starting point from which Islam was propagated along the trade routes in the region. There is no clear indication of when Islam first came to the region, but the first Muslim gravestone markings have been dated to 1082.
When Marco Polo visited the area in 1292 he noted that the urban port state of Perlak was Muslim, Chinese sources record the presence of a Muslim delegation to the emperor from the Kingdom of Samudra (Pasai) in 1282, other accounts provide instances of Muslim communities present in the Melayu Kingdom for the same time period while others record the presence of Muslim Chinese traders from provinces such as Fujian. The spread of Islam generally followed the trade routes east through the primarily Buddhist region and a half century later in the Malacca's we see the first dynasty arise in the form of the Sultanate of Malacca at the far end of the Archipelago form by the conversion of one Parameswara Dewa Shah into a Muslim and the adoption of the name Muhammad Iskandar Shah after his marriage to a daughter of the ruler of Pasai. In 1380, Sufi orders carried Islam from here on to Mindanao.
Another driving force for the change of the ruling class in the region was the concept among the increasing Muslim communities of the region when ruling dynasties to attempt to forge such ties of kinship by marriage. By the time the colonial powers and their missionaries arrived in the 17th century the region up to New Guinea was overwhelmingly Muslim with animist minorities.