ニケフォロス1世
Kubrat, in 635, according to Nikephoros I, "ruler of the Onoğundur–Bulğars, successfully revolted against the Avars and concluded a treaty with Heraclius". The state Old Great Bulgaria (Magna Bulgaria) was formed. Kubrat died "when Konstantinos was in the West", somewhere during the reign of Constans II (641–668).