An oligarchy may derive its power from social posi tion, wealth, military might or even religion. Most 20thcentury oligarchies have been based on military or po litical power. Juntas, small groups of military officers, frequently seized power in Latin America, and a junta ruled Greece from 1967 to 1975. The governments of many communist nations were oligarchies, with politi cal control in the hands of a few Communist Party lead ers. Many 20th-century oligarchies evolved into dicta torships as one member seized power.