The use of Anatolian designations has varied over time, perhaps originally referring to the Aeolian, Ionian and Dorian colonies situated along the eastern coasts of the Aegean Sea, but also encompassing eastern regions in general. Such use of Anatolian designations was employed during the reign of Roman emperor Diocletian (284-305), who created the Diocese of the East, known in Greek as the Eastern (Ανατολής / "Anatolian") Diocese, but completely unrelated to the regions of Asia Minor. In their widest territorial scope, Anatolian designations were employed during the reign of Roman emperor Constantine I (306-337), who created the Praetorian prefecture of the East, known in Greek as the Eastern (Ανατολής / "Anatolian") Prefecture, encompassing all eastern regions of the Late Roman Empire, and spaning from Thrace to Egypt.