Great Moravia briefly regained control over the emerging Bohemian principality upon Bořivoj's death in 888/890 until, in 895, his son Spytihněv together with the Slavník prince Witizla swore allegiance to the East Frankish king Arnulf of Carinthia in Regensburg. He and his younger brother Vratislaus then ruled over Central Bohemia around Prague. They were able to protect their realm from the Magyar forces which crushed an East Frankish army in the 907 Battle of Pressburg during the Hungarian conquest of the Carpathian Basin. Cut off from Byzantium by the Hungarian presence, the Bohemian principality existed as independent state though still in the shadow of East Francia; the dukes paid tribute to the Bavarian dukes in exchange for the confirmation of the peace treaty. Vratislaus' son Wenceslaus, who ruled from 921, was already accepted as head of the Bohemian tribal union; however, he had to cope with the enmity of his neighbour Duke Arnulf of Bavaria and his mighty ally, the Saxon king Henry I of Germany. Wenceslaus maintained his ducal authority by submitting to King Henry in 929, whereafter he was murdered by his brother Boleslaus.