The existing seat of government of Kalamansig was formerly the municipality of
Lebak. The first attempt to separate was on Lebak (presently Kalamansig) was under the municipal district of Kiamba while Salaman (now Lebak) use under the district of Dinaig on August 18, 1947, under Executive Order No. 82. and it was again reunited under one independent municipality of Lebak on December 31, 1948. The seat of government was transferred to Salaman on April 12, 1951. Ten years later, the Municipality of Kalamansig formally created by the virtue of Executive Order No. 459 dated December 29, 1961 signed by
Carlos P. Garcia, creating the municipality of Kalamansig from certain barangays of Lebak and Palimbang. There are 20 barangays and sitios carved out from Lebak: • Lun, • Pitas, • Dansalan, • Pedtegenan, • Madu, • Port Lebak, • Lenek, • Santa Clara, • Sebayor, • Nalilidan, • Bosawon, • Calubcub, • Camp III, • Poral, • Limulan, • Simsiman, • Cadiz, • Tipudos. The 8 barangays and sitios were taken from
Palimbang are Sangay, Mat, Danawan, Paril, Babancao, Basiawan, Narra and North Kulaman. Kalamansig was transferred from Cotabato province to province of
Sultan Kudarat on November 22, 1973, by Presidential Decree No. 341 by President
Ferdinand Marcos. Kalamansig lies the few miles from the epicenter of the devastating
1976 Moro Gulf earthquake. On February 17, 1989, barangays Buenaflores, Bugso, Kiadsam, Kadi, Kulaman, Malegdeg and Sewod were excised from Kalamansig to become part of the new municipality of
Senator Ninoy Aquino, by virtue of
Republic Act No. 6712. In 2004, gigantic
shipworms were discovered by the locals within the municipal waters. In 2017, the shipworms were formally researched on by local and international scientists. The research confirmed that the
giant Kalamansig tamilok is
kuphus polythalamia and is the largest species of its kind in the world. Due to the research, Kamalansig became the first and only known permanent natural habitat of the endangered species. ==Geography==