The Byzantine Empire was ruled by the Isaurian dynasty from 717 to 802. The Isaurian emperors were successful in defending and consolidating the empire against the caliphates after the onslaught of the early Muslim conquests, but were less successful in Europe, where they suffered setbacks against the Bulgars, had to give up the Exarchate of Ravenna, and lost influence over Italy and the papacy to the growing power of the Franks.