Final answer:
The Greek city-states were like small independent countries, isolated geographically by mountains and seas but united culturally, despite periods where they were under the control of Hellenistic kingdoms. They had diverse governmental systems and contributed to a shared Greek civilization across the Mediterranean.
Step-by-step explanation:
The Greek city-state, also known as a polis, functioned much like a small independent country with its own unique political structures and culture. The geographical landscape of Greece, characterized by mountains and seas, indeed made each city-state relatively isolated. This contributed to their individual development and the maintenance of independence for many. The seas, including the Mediterranean, were vital for trade and communication among the Greeks and with other civilizations. However, during the Hellenistic period, most Greek city-states were no longer independent, being under the control of various Hellenistic kingdoms, except for the cities in leagues such as the Achaean and Aetolian, which fiercely maintained their autonomy against the Antigonid rulers of Macedon.
The unique political institutions of Greek city-states like Athens, which developed a form of democracy, and the cultural achievements united these city-states in spite of their independence. The Greeks created a common civilization that spread across the Mediterranean, united by culture as opposed to a central governing empire. The characteristics of the city-states and their relative independence from each other led to a diversity in the development of governmental systems, including democracy, oligarchy, and tyranny, among others.