Funny how you only hear complaints about European colonialism, but not a word about Muslim colonialism, that spread from Arabia, to Northern Africa, all the way to Indonesia.
Islam spread into Indonesia through Muslim traders from India and Arabia and by later some Indonesian elites adopting Islam with that generating adoption of Islam by lower classes (to be “in sync” with ruling classes); but it was not spread by Arab or Muslim military conquest as it was in so much of the Middle East. Prior to Islam in Indonesia religion there was a mix of local beliefs with some import of Bhuddism and Hindu beliefs; and Islam there contains some ad mixture of those beliefs, just as Islam in Iran did not eradicate Zoroastrianism within it.