Since the beginning of antiquity, monarchy confronted several republican forms of government, wherein executive power was in the hands of a number of people that elected leaders in a certain way instead of appointing them by hereditary succession. During the archaic period (c. 750–500 BCE), kingship disappeared in almost all Greek poleis, and also in Rome (then still a barely significant town). After the demise of kingship, the Greek city-states were initially most often led by nobility (aristocracy), after which their economic and military power base crumbled. Next, in almost all poleis tyrants usurped power for two generations (tyranny, 7th and especially 6th century BCE), after which gradually forms of governments led by the wealthy (oligarchy) or assemblies of free male citizens (democracy) emerged in Classical Greece (mainly after 500 BCE). Athenian democracy (6th century–322 BCE) is the best-known example of the latter form; classical Sparta (c. 550–371 BCE) was a militaristic polis with a remarkable mix between monarchy (dual kingship), aristocracy (Gerousia) and democracy (Apella); the Roman Republic (c. 509–27 BCE) had a mixed constitution of oligarchy, democracy and especially aristocracy. The city-states of the Etruscan civilization (which arose during the Villanovan period, c. 900–700 BCE) appear to have followed a similar pattern, with the original monarchies being overthrown and replaced by oligarchic republics in the 5th and 4th centuries BCE.