City-states were political units made up of a city and surrounding lands, formed by geography. The two most famous Greek city-states were Athens and Sparta. Athens valued intellectual strength and had the first democratic government. Boys were taught from age 6 and became citizens at 18, then served 2 years in the army. Sparta valued physical strength and its professional army dominated Greece from 600-371 BC. Spartan boys underwent harsh military training from age 7 and only the strongest newborns were accepted.