While this article is about Javanese Islam, the history it describes is just as applicable to Islam elsewhere in Southeast Asia including my country of birth, Malaysia. The Muslims of Southeast Asia used to be Hindus and had rich, syncretic cultural traditions before they converted to Islam primarily through trade rather than conquest. As a result, there has until recently been a strain of relatively greater tolerance and pluralism in Southeast Asian Islam. This is not to suggest that there has not been any discord between Islamic and non-Islamic groups in the region, but in the case of Indonesia and Malaysia this has been partly because religious differences track ethnic differences with the economically dominant non-Muslim Chinese copping the resentments that come with being a ‘middleman minority’.
However a lot of that is now in the past with my admittedly non-specialist impression from reading and family back in Malaysia being that Southeast Asian Islam is becoming increasingly rigidified by more recent cross-polination with its Arab variety, just as this article suggests:
Islam was a relatively recent import to this part of the world. It washed up on the western tip of present-day Indonesia in the twelfth century, took root in the fifteenth, and became dominant across much of the archipelago as late as the seventeenth. For the most part, it arrived through trade rather than conquest, by Indian dhow rather than Arab charger. It was preceded by more than a millennium of Hinduism and Buddhism, whose achievements included Borobudur, a massive ninth-century Buddhist stupa, and Majapahit, a Hindu-Buddhist empire whose influence stretched to present-day Cambodia. As the anthropologist Clifford Geertz wrote in comparing Indonesia to Morocco: “In Indonesia Islam did not construct a civilization, it appropriated one.” …
Historically, the Javanese had not confused being Muslim with being Arab. They had bent Islam to their culture rather than the other way round. In Among the Believers: An Islamic Journey, V. S. Naipaul writes: “It was as if, at this far end of the world, the people of Java had taken what was most humane and liberating from the religions that had come their way, to make their own.”
They had taken the best of Islam, its simple egalitarianism, its ability to infuse drab lives with dignity, without devaluing their earlier achievements. The Javanese retained their own history and architecture, their own names, their own dress and dance and music, their own rituals at birth and marriage and death, even their own conception of the afterlife. It was these, expressed in a million subtle ways in gesture and carriage and voice, that gave their civilization such a high gloss at what remained, after all, a very low level of income.
It was these that the wave of orthodox Islam that had washed over Indonesia in the last thirty-odd years threatened to extinguish.