According to local folklore, the archipelago was discovered by Sunan Nyamplungan (Amir Hasan), a son of one of the
Wali Songo, the nine saints who brought
Islam to Java. He is said to have settled on the main island to spread his father’s teachings. His tomb on Karimunjawa is an important place of pilgrimage. Archeological finds of Chinese ceramics on the seabed near the islands which date from around the 13th century suggest that the islands were once part of a trade route to Java. Apart from use as a
pirate base, the islands are believed to have been uninhabited until a penal settlement was established during the British occupation of Java in the early nineteenth century. In 1818,
the Netherlands appointed a
Prussian nobleman named Carel Rudolph von Michalofski (1792–1854) as post holder of the islands. His first task was to drive out the pirates who were rife there. He then had to establish a
nagari on the islands with 1,100
convicts. Within fifteen years, he managed to transform the notorious pirate’s den into a thriving archipelago. The settlement was temporarily abandoned by the Dutch during the
Java War of 1825–1830, but the former convicts remained as
settlers. Coconut plantations set up during the convict period became a major source of income, as did fishing. The islands were declared a
national park in 1988. ==Geology and climate==