As the power of the Western Turks faded in the 600s the Avars reasserted their domination over the Bulgars. Between 630 and 635 Khan Kubrat of the Dulo clan managed to unite the main Bulgar tribes and to declare independence from the Avars, creating a powerful confederation called Old Great Bulgaria, also known as Patria Onoguria, between the Black Sea, the Sea of Azov and the Caucasus. Kubrat, who was baptised in Constantinople in 619, concluded an alliance with the Byzantine Emperor Heraclius (r. 610–641) and the two countries remained in good relations until Kubrat's death between 650 and 665. Kubrat fought with the Khazars in the east but after his demise Old Great Bulgaria disintegrated under strong Khazar pressure in 668 and his five sons parted with their followers. The eldest Batbayan remained in his homeland as Kubrat's successor and eventually became a Khazar vassal. The second brother Kotrag migrated to the middle Volga region and founded Volga Bulgaria. The third brother Asparuh led his people west to the lower Danube. The fourth one, Kuber, initially settled in Pannonia under Avar suzerainty but revolted and moved to the region of Macedonia, while the fifth brother Alcek settled in central Italy.