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The classical period of Greek civilization covers a time spanning from the early 5th century BC to the death of Alexander the Great, in 323 BC (some authors prefer to split this period into 'Classical', from the end of the Persian wars to the end of the Peloponnesian War, and 'Fourth Century', up to the death of Alexander). It is so named because it set the standards by which Greek civilization would be judged in later eras. The Classical period is also described as the "Golden Age" of Greek civilization, and its art, philosophy, architecture and literature would be instrumental in the formation and development of Western culture.

What did the Greeks do that made it possible for the expansion and growth of the opposite of the Eastern Civilization ?
civilization, and its art, philosophy, architecture and literature would be instrumental in the formation and development of Western culture.