High Quality Content by WIKIPEDIA articles! Basilan is an island province of the Philippines. It is the largest and northernmost of the major islands of the Sulu Archipelago and is located just off the southern coast of Zamboanga Peninsula. Its capital is Isabela City. Basilan is home to three main ethnic groups, the indigenous Yakans, and the later-arriving Tausugs and Chavacanos. The Yakans and Tausugs are predominantly Muslim, while the Chavacanos are mainly Christian. There are also a number of smaller groups.