Complex sentence: Indigenous Lumad, mostly refugees from the conflict-plagued island of Mindanao, gathered to condemn the human rights abuse and the maltreatment of their people by the Philippine Army alleging that members of the indigenous tribes are supporters of the communist New People's Army.
Split into simpler sentences: Indigenous Lumad, mostly refugees from the conflict-plagued island of Mindanao, gathered to protest against the Philippine Army which they accuse of committing human rights abuse against their people. The Philippine Army alleges that members of the indigenous tribes are supporters of the communist New People's Army.