The Greek 'polis' or 'city-state' emerged from the Greek Dark Ages following the destruction of the Mycenaean civilization and the subsequent decline in the powers of kings. The polis was a state of a small size, both in territory and in population, which demanded the active participation of all citizens in its affairs.
It was thus regarded as the sum of its citizens; the Spartan polis, for instance, was not 'Sparta' but 'The Spartans'. In physical terms, the polis was essentially a walled city which had an Acropolis, Agora, and Bouleuterium.
Every polis had territory outside of its walls which was governed from the city. Each had its own laws, traditions, political and social structures, cults, festivals, and magistrates. This made every polis distinctly different, and each one strove hard to maintain its independence and freedom.
Several hundred of these city-states existed throughout Greece, and Greek colonists founded new 'poleis' wherever they went. The polis declined in the 4th century BC due to inter-state wars, economic decline, mercenary armies (which replaced citizen armies) and the rise of Macedon as a world power under kings Philip II and Alexander the Great.
