Aztecs: A Nahuatl-speaking tribe of Indians who dominated much of Mexico at the time of the Spanish conquest (1519-1521) under Hernan Cortez. In the 12th century, the Aztecs moved into the valley of Anahuac from the northwest and gradually subdued neighboring tribes, turning them into tribute-paying vassals. The “emperor” of the Aztecs was chosen by a supreme council, which represented the twenty clans that comprised the Aztec tribe.
Excerpted from: Murphy, Bruce, ed. Benet’s Reader’s Encyclopedia, Fourth Edition. New York: Harper Collins, 1996.