Classical civilizations are civilizations that influence subsequent societies. The four classical civilizations had a great impact on many other civilizations. Another example of classical civilization besides Greece is Rome. Classical civilizations have had both a positive and negative effect on the modern world. From approximately 1750 to 133 BC, gender-based discrimination arose in classical Greece. As Greece developed, it did not form a centralized government, but instead formed a collection of city-states, or polis. Due to Greece's mountainous terrain, the empire was not unified, and upper-class men ruled each city-state. As a result of Greece's isolation, each city-state developed different cultures, such as Athens and Sparta. Due to the different cultures throughout Greece, gender roles differed from polis to polis. As Greece adopted ideas from Mesopotamia and Egypt, Greek poleis developed as generally patriarchal, although women were afforded slightly greater rights than in earlier societies. Some Greek city-states developed as more patriarchal than others...