FFROM THE TIME OF THE MYCENAEANS, violent conflict was common in Greek society, and this did not change in the fifth century B.C.E., the beginning of what scholars later called the classical period of Greek history, which they date from about 500 B.C.E. to the conquest of Greece by Philip of Macedon in 338 B.C.E. First, the Greeks beat back the armies of the Persian Empire. Then, turning their spears against one another, they destroyed their own political system in a century of warfare culminating in the Peloponnesian War. This war and its aftermath proved that the polis had reached the limits of its success as an effective political institution. The Greeks’ failure to unify against outsiders led to the rise of a dominant new power: the kingdom of Macedonia.