The ancient civilization of Greece was located in southeastern Europe along the coast of the Mediterranean Sea. Its geography was full of mountains; in fact, around 80% of the Greek mainland is mountainous.
Such mountainous geography, along with seas and islands, contributed to Greece's development as a group of individual city-states since these mountains and seas formed natural barriers between the Greek city-states, making it difficult to make long journeys by land and forcing the Greeks to settle along the coast.