Democracy in its broadest sense likely began in small hunter-gatherer groups where decisions were made by consensus or majority, a form of proto-democracy seen in prehistoric times. However, the concept and practice of democracy as a formal political system first originated in ancient Athens around the 6th century BCE (circa 508 BCE) under the leadership of Cleisthenes, often called "the father of Athenian democracy." This Athenian democracy is considered the first known example of a system where citizens had political equality and a role in governing, contrasting with aristocracy, monarchy, or tyranny.