Peloponnesian League
The major cities of Sparta, Corinth, Argos and Megalopolis were all located on the Peloponnese, and it was the homeland of the Peloponnesian League. Soldiers from the peninsula fought in the Persian Wars, and it was also the scene of the Peloponnesian War of 431–404 BC. The entire Peloponnese with the notable exception of Sparta joined Alexander's expedition against the Persian Empire.