Much like the larger Mauro-Roman Kingdom, the Kingdom of the Aurès combined aspects of Roman and Berber culture in order to efficiently rule over a population composed of both Roman provincials and Berber tribespeople. For instance, King Masties used the title of "Dux" and later "Imperator" to legitimize his rule and openly declared himself a Christian. Despite this, Aurès would not recognize the suzerainty of the remaining Roman Empire in the East (often called the Byzantine Empire by modern historians) and King Iabdas unsuccessfully invaded the Praetorian prefecture of Africa, established after the Byzantines had defeated the Vandals. One possible reason towards why the Berbers could not be integrated as successfully into the Byzantine Empire as they had been before was the Byzantine shift in language from Latin to Greek, the Berbers were thus no longer bilingual with the language of their nominal rulers.