MYGDONIA (anc. geog.), a district of Macedonia, to the north of the Sinus Thermaicus, and east of the river Axius, which separates it from Bottiazis, and west of the river Strymon, (Pliny.) Also a district of Mesopotamia, which took its name from that of Macedonia, running along the Euphrates, from Zeugma down to Thapiacus, extending a great way east, because Nisibis was reckoned to it.