The Roman provinces (Latin: provincia, pl. provinciae) were the administrative regions of Ancient Rome outside Roman Italy that were controlled by the Romans under the Roman Republic and later the Roman Empire. Each province was ruled by a Roman appointed as governor.
For centuries, it was the largest administrative unit of the foreign possessions of ancient Rome. With the administrative reform initiated by Diocletian, it became a third level administrative subdivision of the Roman Empire, or rather a subdivision of the imperial dioceses (in turn subdivisions of the imperial prefectures).
