Zamboanga Peninsula is an administrative region in the Philippines, designated as Region IX. The region consists of three provinces (Zamboanga del Norte, Zamboanga del Sur, and Zamboanga Sibugay) and two independent cities (Isabela and Zamboanga City). The region was previously known as Western Mindanao before the enactment of Executive Order No. 36 on September 19, 2001. Pagadian City is the regional center .