"After independence, a separatist movement emerged among students and intellectuals in the late 1960s, gaining popular support after the eruption of communal violence in Cotabato in 1970. The movement developed into an armed struggle for secession after President Ferdinand Marcos declared martial law in 1972. The conflict continued into the mid-1970s, with a cease-fire declared and Libyan-brokered peace talks held in 1976. The settlement offered to the separatists included a Muslim Autonomous Region in 13 provinces, but negotiations broke down. Marcos began implementing parts of the 'Tripoli Agreement' unilaterally, including passing a Code of Muslim Personal Laws in 1977."
http://www.law.emory.edu/IFL/legal/philippines.htm
"In December 1976, with the aid of Libya, and under the auspices of the Organization of Islamic Conference (OIC), Philippine government officials and MNLF leaders negotiated a settlement known as the Tripoli Agreement. The agreement included a ceasefire and the granting of autonomy to thirteen provinces where the majority of Muslims lived. However, the Tripoli agreement was never genuinely implemented by the Marcos regime. As a consequence, fighting broke out once more before the end of 1977, but did not again approach the level of intensity experienced prior to the ceasefire. The Muslim separatist movement entered a period of disarray marked by factional infighting (including the founding of the MILF) and a weakening of popular support. By the early 1980s the separatist struggle gradually transformed itself into a popular, mostly unarmed movement."
http://fpif.org/selfdetermination/conflicts/philippines_body.html