It was during the reign of the Byzantine Emperor Heraclius (610-41) that the pivotal event of Islamic history took place-when a former caravan merchant called Mohammed took refuge in Medina after being driven out of Mecca. The event is called the Hegira or migration and its date, 622 AD, marks the beginning of the Muslim calendar. But Heraclius was distracted by what seemed far greater matters. During the first ten years of his reign the Persians
Had made frightening advances against his empire.
The Persian state religion was Zoroastrianism and wherever it spread, Christianity was persecuted. Antioch fell to the Persians in 611, Damascus in 613, Jerusalem in 614 and Alexandria in 619. Moreover, after slaughtering Jerusalem's 67,000 Christian inhabitants the Persians made off with the True Cross, Christendom's holiest relic-and it was this which turned Heraclius' 622 campaign against the Persians into something new, as it included a crusading zeal. In 627 as Heraclius advanced deep into Persia, its king was overthrown by revolution and his successor sued for peace. Byzantium's eastern provinces were restored to the empire and the True Cross was returned to Jerusalem.
But the Byzantines in their victory and the Persians in defeat both lay exhausted when the sounds of war were heard again. This time it was the army of Umar-Arab followers of the new religion of Islam-who in 633 declared a jihad, a holy Islamic war, against the Byzantine Empire. Mohammed had died the previous year, and the Byzantines, to the extent that they knew anything about slam at all, mistook it for a revival of Arianism, a familiar Christian heresy which depreciated the divinity of Jesus, and did not feel greatly threatened, failing to recognise the approaching Bedouins as a significant military force.
World History
