The Principality of Serbia or Serbian Principality (Serbian: Cрпска кнежевина / Srpska kneževina), also known as Raška (Рашка, Latin: Rascia), was an early medieval state of the Serbs ruled by the Vlastimirović dynasty, that existed from 7th century to 969 in Southeastern Europe. Its first ruler known by name was Višeslav. In 822, the Serbs were said to rule the "greater part of Dalmatia", and at the same time the Bulgars had taken the lands to the east, preparing to conquer Serbia. Vlastimir defeated the Bulgar army in a three-year-war (839–842), and the two powers lived in peace for some decades. Vlastimir's three sons succeeded in ruling Serbia together, although not for long; Serbia became a key part in the power struggle between the Byzantines and Bulgars (in predominantly Byzantine a