The Greek polis was not the first form of city-state to emerge. The earliest states in Sumer were also city-states, as were many of the small Mycenaean kingdoms. What differentiated the new Greek model from older city-states is the fact that the polis was more than a political institution; it was a community of citizens with their own customs and laws. With one exception, the poleis that emerged after 800 did not have kings but instead were self-governing. The physical, religious, and political forms of the polis varied from place to place, but everywhere the polis was relatively small, reflecting the fragmented geography of Greece. The very smallness of the polis enabled Greeks to see how they fit individually into the overall system — and how the individual parts made up the social whole. This notion of community was fundamental to the polis and was the very badge of Greekness.

Poleis developed from Dark Age towns, which were centers of administration, trade, and religion. When fully developed, each polis normally shared a surprisingly large number of features with other poleis. Physically a polis was a society of people who lived in a city (asty) and cultivated the surrounding countryside (chora). The countryside was essential to the economy of the polis and provided food to sustain the entire population. The city’s water supply came from public fountains, springs, and cisterns. By the fifth century B.C.E. the city was generally surrounded by a wall. The city contained a point, usually elevated, called the acropolis, and a public square or marketplace called the agora (ah-guh-RAH). On the acropolis, which in the Dark Age was a place of refuge, people built temples, altars, public monuments, and various dedications to the gods of the polis. The agora was the political center of the polis. In the agora were shops, public buildings, and courts.

All poleis, with one exception, did not have standing armies. Instead they relied on their citizens for protection. Wealthy aristocrats often served as cavalry, which was never very important in military conflicts. The backbone of the army was the heavily armed infantry, or hoplites, ordinary citizens rather than members of the elite. Hoplites wore bronze helmets and leather and bronze body armor, which they purchased themselves. They carried heavy, round shields made of wood covered in bronze and armed themselves with iron-tipped spears and swords. They marched and fought in a close rectangular formation known as a phalanx, holding their shields together to form a solid wall, with the spears of the front row sticking out over the tops of the shields. As long as the phalanx stayed in formation, the hoplites presented an enemy with an impenetrable wall. This meant that commanders preferred to fight battles on open plains, where the hoplites could more easily maintain the phalanx, rather than in the narrow mountain passes that were common throughout much of Greece.