Basilan is a province in the Philippines situated in the Bangsamoro Autonomous Region in Muslim Mindanao occupying the Sulu Archipelago and the provinces of Lanao del Sur and Maguindanao in central Mindanao. Its capital is the City of Isabela.

The province has a land area of 3,453.42 square kilometers or 1,333.37 square miles. Its population as determined by the 2020 Census was 426,207. This represented 9.68% of the total population of the Bangsamoro Autonomous Region in Muslim Mindanao, 1.62% of the overall population of the Mindanao island group, or 0.39% of the entire population of the Philippines. Based on these figures, the population density is computed at 123 inhabitants per square kilometer or 320 inhabitants per square mile.

-https://www.philatlas.com/mindanao/barmm/basilan.html