The FMLN was formed, allegedly with Cuban backing, as guerrilla umbrella organization for five leftist groups active in El Salvador in the 1970s: Central American Workers' Revolutionary Party (PRTC), People's Revolutionary Army (ERP), Farabundo Marti Popular Liberation Forces (FPL), Armed Forces of National Resistance (FARN), and the Communist Party of El Salvador's Armed Forces of Liberation (FAL).
The organization was named for the rebel leader Farabundo Marti, who led workers and campesinos in an uprising to transform Salvadoran society after the devastation caused by the eruption of the volcano Izalco in 1932. It was ruthlessly supressed, with some 30,000 killed.