During the Greek Dark Ages, the Greeks lived in small tribal units; some of these small tribes were sedentary and agricultural and some were certainly nomadic. They had abandoned their cities between 1200 and 1100 BC for reasons that remain shrouded in mystery; the Greeks believed that a cataclysmic and ferocious invasion of northern Greek barbarians, the Dorians, had wiped out the Mycenean civilization. In reality, the decline and abandonment of urbanization in Greece was probably due to a combination of economic collapse and pressure from northern migrations. Greek life during the "Dark Ages" wasn't dark; it was, in fact, a culturally creative period. This period gave the Greeks the religion their religion, mythology, and foundational history in their final forms; the close of the Dark Ages would also gave the Greeks the rudiments of their greatest political achievement: the polis , or "city-state."
The tribal or clan units of the dark ages slowly grew into larger political units; beginning around 800 BC, trade began to dramatically accelerate between the peoples of Greece.
Marketplaces grew up in Greek villages and communities began to gather together into defensive units, building fortifications to use in common. On this foundation, the Greek-speaking people on the Greek peninsula, the mainland, and the coast of Asia Minor, developed political units that were centrally based on a single city. These city states were independent states that controlled a limited amount of territory surrounding the state. The largest of these city-states, for instance, was Sparta, which controlled more than 3000 square miles of surrounding territory.
The period in which the city-states evolved is called the Archaic Period; while the separate states had close interaction with one another during this time and certainly learned political organization from one another, in many ways, however, each city-state developed fairly...