Lanao del Sur (Maranao: Ranao Masarik, Cebuano: Habagatang Lanaw; Filipino: Timog Lanaw), officially the Province of Lanao del Sur, is a province in the Philippines located in the Autonomous Region in Muslim Mindanao (ARMM). The capital is the city of Marawi, and it borders Lanao del Norte to the north, Bukidnon to the east, and Maguindanao and Cotabato to the south. To the southwest lies Illana Bay, an arm of the Moro Gulf.

Situated in the interior of Lanao del Sur is Lanao Lake, the largest in Mindanao. The Darangen Epic Chants of the Maranao of Lanao del Sur is inscribed as a UNESCO Intangible Cultural Heritage since 2008.

"Lanao" means "lake", derived from ranao. The province, situated at basin of Lake Lanao, is known as the land of the "Maranaos" (which means "the "people of the lake").

Lanao was first explored by the Spaniards in 1689, upon which they discovered a well-settled community named Dansalan at the lake's northern end. Lanao was the seat of the Sultanate of Lanao.

During the Pre-Spanish time, there are 4 important boundaries hold the power of appointing a new sultan namely: Bakayawan, Dalama, Madamba and Sawer. In appointing a new sultan the permission of these four boundaries are needed to validate the new sultan appointed to his position.

...
Wikipedia