The flourishing period of the Eastern Empire closes for a long time with
Heraclius, who died in A.D. 641. The Persians and the Turks (Mongolians
from Asia), with their kinsmen the Avars attacked the empire with
formidable strength. Between 611 and 615 the Persians overran Egypt,
Syria and Asia Minor, remaining encamped for ten years within sight of
Constantinople. Heraclius, between 620 and 628, recovered the Persian
conquests.