The island of Timor was possibly known as a source for sandalwood in the 15th century. The first recorded Portuguese voyage to the island from Portuguese Malacca occurred in 1516, returning with sandalwood. In 1521, sandalwood was left out of a list of products under royal monopoly, leaving most trade with Timor in the hands of private enterprises. Portuguese and Spanish interest in the island increased in the 1520s, with regular trade established by 1524. In the late 1500s, administrative officials began to be appointed to nearby Solor with jurisdiction over that island and Timor, signifying increasing state interest in Portuguese activities there. The Netherlands began to compete for control of the island in 1613, especially in the west. A rebellion in 1629 forced the Portuguese off the island for three years. In 1641, a number of kings in Timor converted to Catholicism while seeking Portuguese protection. This introduced a political dimension to Portuguese influence, which had previously been primarily economic.