not withstand the Khazars. They left their country and fled... until they reached the river called Duna (Danube)". This migration and the foundation of the Danube Bulgaria (the First Bulgarian Empire) is usually dated c. 679. The composition of the horde is unknown, and sources only mention tribal names Čakarar, Kubiar, Küriger, and clan names Dulo, Ukil/Vokil, Ermiyar, Ugain and Duar. The Onglos where Bulgars settled is considered northern Dobruja, secured to the West and North by Danube and its Delta, and bounded to the East by the Black Sea. They re-settled in North-Eastern Bulgaria, between Shumen and Varna, including Ludogorie plateau and southern Dobruja. The distribution of pre-Christian burial assemblages in Bulgaria and Romania is considered as the indication of the confines of the Bulgar settlement. In the Balkans they merged with the Slavs and other autochthonous Romance and Greek speaking population, like the Thracians and Vlachs, becoming a political and military elite. However, the influence of the pre-Slavic population had relatively little influence on the Slavs and Bulgars, indicating their population was reduced in previous centuries. The hinterlands of the Byzantine territory were for years occupied by many groups of Slavs. According to Theophanes, the Bulgars subjugated the so-called Seven Slavic tribes, of which the Severeis were re-settled from the pass of Beregaba or Veregava, most likely the Rish Pass of the Balkan Mountains, to the East, while the other six tribes to the Southern and Western regions as far the boundary with the Pannonian Avars. Scholars consider that the absence of any source recording the Slavic resistance to the invasion was because it was in their interest to be liberated from the Byzantine taxation. It is considered that the Slavic tribal organization was left intact, and paid tribute to the ruling Bulgars. According to Nikephoros I and Theophanes, an unnamed fourth brother, believed to be Kuber, "having crossed the river Ister, resides in Pannonia, which is now under the sway of the Avars, having made an alliance with the local peoples". Kuber later led a revolt against the Avars and with his people moved as far as the region of Thessaloniki in Greek Macedonia. The fifth brother, reported by Nikephoros I and Theophanes, "settling in the five Ravennate cities became a subject of the Romans". This brother is believed to be Alcek, who after a stay in Avar territory left and settled in Italy, in Sepino, Bojano