Ancient Myonia made its mark on the ruins of the fortifications surrounding the modern city of Agia Efthymia, on the southern foothills of Mt Giona. The region has been inhabited since Mycenaean times, while it is mentioned by Thucydides in the Peloponnesian War, as well as by Pausanias, who described the sacrifices made at the altar of the Meilichioi Gods. He mentions the existence of a temple dedicated to Poseidon and describes the assignment of a shield by the locals to Olympian Zeus which was included in the Treasury of the Sicyonians.