Eion (Greek, Ancient (to 1453);: Ἠϊών) was a town in ancient Thrace. It was a colony of the Mendaeans, which was betrayed to the Athenians, and retaken by the Chalcidians and Bottiaeans in 425 BCE. Eustathius placed Eion in the Chersonesus,[1] but, as William Smith suggests that was much too remote for the Chalcidians to have marched to recover a town, Eion must have been on some point of the long and winding coast which extends from the Strymon River to the Axius River.