The Turkic-speaking Bulgars arrived in the territories west of the river Dniester around 670. At the Battle of Ongal they defeated the Eastern Roman (or Byzantine) Emperor Constantine IV in 680 or 681, occupied Dobruja and founded the First Bulgarian Empire. They soon imposed their authority over some of the neighboring tribes. The great variety in burial rites evidences the multi-ethnic character of the Bulgarian Empire. Even the Bulgars were divided in this respect; some of them practiced inhumation and others cremation. Initially, a sharp distinction existed between the Bulgars and their subjects, but the Slavicization of the Bulgars soon began.