The Muslim/Mindanao Independence Movement was founded by the former governor of Cotabato, Datu Udtog Matalam, to which the establishment of an Islamic Republic of Mindanao and Sulu was the main objective. This was founded due to the Corregidor incident also known as the Jabidah Massacre that took place on March 17, 1968. Blackshirts became the name of the military arm of this group.

Source: Peter G. Gowing, Muslim Filipinos; Heritage and Horizon