By the 630s, Sassanid Persia had descended into a state of civil war, while Byzantium, under the aging emperor Heraclius, its manpower and resources depleted in the struggle with its old adversary, was struggling to re-establish its authority in its newly re-conquered eastern provinces. The two states were thus in considerable internal turmoil, and unable to either stop the Muslim expansion or to recover from its first blows. It is unknown whether Umar intended from the outset to conquer both the Sassanid and the Byzantine Empire, or simply allowed raids, and then, perceiving their weakness, followed up with full-scale invasion.
By the 630s, Sassanid Persia was in civil war while Byzantium, under the aging emperor Heraclius, its manpower and resources depleted in the struggle with its old adversary, was struggling to re-establish its authority in its newly re-conquered eastern provinces. The two states were thus in considerable internal turmoil, and unable to either stop the Muslim expansion or to recover from its first blows. It is unknown whether Umar intended from the outset to conquer both the Sassanid and the Byzantine Empire, or simply allowed raids, and then, perceiving their weakness, followed up with full-scale invasion.