Province of Indonesia in northern Sumatra. Some historians believe that Islam first came to Indonesia through Aceh in approximately the ninth century and that Aceh was the site of the first Muslim sultanate in the islands. It became a regional power in the seventeenth and eighteenth centuries but was conquered by the Dutch at the beginning of the twentieth century after a lengthy war. After Indonesia declared its independence in 1945 the Acehnese frequently challenged the republic's legitimacy and continue to demand autonomy or independence. Approximately 98 percent of Acehnese are Muslims and are known for their strong devotion to Islam.