According to history, Maasim was actually a combination of two words, Ma and Sim which were derived from the names of a brook called Ma and an old B'laan Chieftain Sim

    In early 1800, the Muslims were the first settlers of Maasim where settlements were found in Barangay Pananag and Barangay Kanalo founded by Datu Aman and Datu Calusisi, one of the children of Malinog Balindong Karamat of Glan (formerly Galang).

    On the other hand, another muslim tribe known as Samal also inhabited Barangay Lumatil. Although there is no accurate historical facts of their origin, this writer believes that this muslim tribe might have settled the place during the migration of Samals from Bonggo Islands, Cotabato to the Gulf of Davao and Sarangani Islands in Davao del Sur.

    In 1926, during the American regime, a certain Florentino Panerio, together with some settlers from Glan expedited and crossed Sarangani Bay by a small banca to look for a fertile soil to till and eventually landed in Cucob, Kanalo but finally settled in Kablacan.

    Two years after in 1929, another group of settlers have followed and with the massive migration of settlers and homeseekers. Kablacan was virtually made as a center of the economic and political activities of the municipality. However,  some of those have moved to the eastern part of the municipality particularly to Poblacion, Colon, Malbang and Kamanga..

    The migration marked the highest peak of development in the current history of Maasim. This time the eastern side of the town is being densely populated.

    With the progressive leadership of barangay leaders of Poblacion, Kablacan and Colon who jointly agreed to ask the national government to separate Maasim from its mother municipality (Kiamba) and create into a new regular municipality, President Diosdado Macapagal issued Executive Order No. 113 creating Maasim into a regular municipality in 1965. Subsequently, in October 1965, barely one month before the scheduled national election, the President appointed and administered the oath of office of Mr. Felipe Uy as Mayor together with his Vice Mayor and five councilors.

    However President Ferdinand  Marcos dissolved the newly created municipality as a consequence to former Vice-President Emmanuel Pelaez's question on the validity and authority of Pres. Macapagal's act of creation. The issue has reached the level of the Supreme Court of the Philippines, which ruled out that the creation was beyond the authority of the President, but by the Legislative Branch (Congress) of the government.

    At the turn of fate, during the regular session of the Congress of the Philippines on January 27, 1969, Congressman Chiongbian of the lone district of South Cotabato intoduced the Bill for the re-creation of the municipality of Maasim consistent to its development and was approved on June 21, 1969 through Republic Act No. 5866.

    Subsequently, thereafter on November 8, 1971, Hon, Jaime F. Arizaleta became the first elected Mayor of the newly created municipality of Maasim until the appointment of OIC-Gregorio A. Zamorro, Sr. as an aftermath of the 1996 EDSA People Power Revolution.

    The Administration of Aniceto Lopez, Sr. came to power upon his election in 1988 and continued to reign until his three consecutive term ended when his Vice-Mayor Moises A. Zamorro, Sr. succeeded him in the 1998 elections.

    After Zamorro, Sr.'s refusal to go for a reelection, the very own son of his predecessor, Hon. Aniceto P. Lopez, Jr., catapulted to power having been elected as mayor of the municipality in the 2001 elections.