Lanao del Sur is a province of the Philippines located in the Autonomous Region in Muslim Mindanao (ARMM). Its capital is Marawi City and 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. Found in the interior of Lanao del Sur is Lanao Lake, the largest lake in Mindanao.
Lanao del Sur forms the western portion of Northern Mindanao. It is bounded on the north by Lanao del Norte, on the east by Bukidnon, on the west by Illana Bay, and on the south by Maguindanao and Cotabato. The landscape is dominated by rolling hills and valleys, placid lakes and rivers.
The climate in the province is characterized by even distribution of rainfall throughout the year, without a distinct summer season. The province is located outside the typhoon belt.
Lanao comes from the word ranao, meaning “lake.” Lanao centers on the basin of Lake Lanao; thus, it is the land of the Maranaos, the “people of the lake.”
When the Spaniards first explored Lanao in 1689, they found a well-settled community named Dansalan at the lake’s northern end. Dansalan became a municipality in 1907 and a city in 1940, in 1942, occupied from the Japanese Imperial forces landed in Southern Lanao, in May 2, 1942, the former chief justice of the supreme court of the Philippines Jose Abad Santos he was killed by the Japanese Imperial forces by the Firing Squad at Malabang, Lanao del Sur, in 1945. The first of the liberation forces landed in Southern Lanao and entered with the United States and the Philippine Commonwealth troops together with the Maranao guerrilla units, who used the infantry weapons together with the Maranao Kris, Barong and Kampilan swords against the Japanese forces during in the Battle of Lanao, although it was inaugurated as such only in 1950. In 1956, Republic Act NO. 1352 changed the name Dansalan to Marawi, from the word rawi, referring to the reclining lilies in the Agus River.
When Lanao was divided into two provinces under Republic Act No. 2228 in 1959, Marawi was made the capital of Lanao del Sur. In 1980, the city was renamed the Islamic City of Marawi. It is now the only chartered city in the country with a predominantly Muslim population.
In a 1989 plebiscite, Lanao del Sur voted to join the Autonomous Region of Muslim Mindanao (ARMM), but Marawi City elected to remain outside ARMM. It later joined in 2001 following the plebiscite that sought to expand the autonomous region.