Island (pop., 2007 prelim.: 21,073,500), southern Philippines. The second largest island in the Philippines, it has an area of 36,537 sq mi (94,630 sq km); it is 324 mi (521 km) long and 293 mi (471 km) wide. It is mountainous and contains active volcanoes, including Mount Apo, the highest peak in the Philippines. The rare Philippine eagle is unique to the island. Islam spread throughout Mindanao in the 15th century. It was visited by Ferdinand Magellan in 1521. It was later claimed by Spain, but the resistance of its Muslim inhabitants kept it largely independent of Spanish authority. The autonomous region of Muslim Mindanao, in the western and southwestern portions of the island, was created in 1990.