Epeiros, sometimes ‹Apeiros› in the sources, was a region in the northwest of the ancient Balkan peninsula. It ran roughly from the Gulf of Ambrakia in the south to Apollonia in the north, and as far inland as the Pindos mountain range. Epeiros was a region of substantial political and ethnic variety. For instance, Thucydides (2. 80. 5–6), when relating the local forces campaigning with the Spartan admiral Knemos in Akarnania in the summer of 429, describes a variety of ‹barbarian› contingents from Epeiros, some coming from communities with kings (Molossians, Atintanians, Parauaians, Orestians) and others kingless (Chaonians, Thesprotians). Three of these ethne came to dominate the region in the fourth, third, and second centuries: the Molossians, the Thesprotians, and the Chaonians. The Molossians and their ruling house, the Aiakids, appear most frequently in our standard narratives: Olympias, mother of Alexander the Great, and Pyrrhos, enemy of Rome, were both Aiakids.