In 442, the area was ravaged by Attila the Hun. In 471, it was taken by Theodoric the Great, king of the Ostrogoths, who continued into Italy. As the Ostrogoths left, another Germanic tribe, the Gepids, invaded the city. In 539 it was retaken by the Byzantines. In 577, some 100,000 Slavs poured into Thrace and Illyricum, pillaging cities and more permanently settling the region. The Avars, under Bayan I, conquered the whole region and its new Slavic population by 582. Following Byzantine reconquest, the Byzantine chronicle "De Administrando Imperio" mentions the White Serbs, who had stopped in Belgrade on their way back home, asking the "strategos" for lands; they received provinces in the west, towards the Adriatic, which they would rule as subjects to Heraclius (610–641). In 829, Khan Omurtag was able to add Singidunum and its environs to the First Bulgarian Empire.