Islam is thought to have been present in Southeast Asia from early in the Islamic era. From the time of the third caliph of Islam, Uthman (644-656), Muslim emissaries and merchants were arriving in China who must have passed through Indonesia sea routes from the Islamic world.
The kingdom of Ratu Kidul, the Queen of the South Seas (‘ratu’ = queen, and ‘kidul’ = south), is called Karaton Bale Sokodhomas, and the center of the kingdom is in the Java Trench, which runs parallel to the south coast of Java and is the deepest part of the Indian Ocean (seven kilometers deep). Her palace is there, below the ocean, directly south from Merapi Mountain and the city of Yogyakarta in Central Java, but her influence covers all of Bali, Java and the southern part of Sumatra. In particular the volcano, Krakatoa, lies within her domain.