Theophanes the Confessor records that in 681 the Byzantine emperor Constantine IV was forced to recognize the independence of a "new and vulgar people" north of the Balkan range. Asparuh's new Bulgar Khanate , subsequently known as the Pârvo Bâlgarsko Tsarstvo - the First Bulgarian Kingdom - was centred at Pliska and ruled over a Danubian state that stretched from the Carpathians in the north to the Balkan Range in the south. Although the Khanate was very much reliant on Slav strength, the Bulgars - whose society was geared to movement and war - definitely provided the impetus for its expansion over the next 150 years.