For much of the subsequent period, Savia was probably directly ruled by the Carinthian Duke Arnulf, the future East Frankish King and Emperor. However, Frankish control was far from smooth. The Royal Frankish Annals mention several Bulgar raids, driving up the Sava and Drava rivers, as a result of a border dispute with the Franks, from 827. By a peace treaty in 845, the Franks were confirmed as rulers over Slavonia, whilst Srijem remained under Bulgarian clientage. Later, the expanding power of Great Moravia also threatened Frankish control of the region. In an effort to halt their influence, the Franks sought alliance with the Magyars, and elevated the local Slavic leader Braslav in 892, as a more independent Duke over lower Pannonia.