The empire that sprang from nowhere under the banner of Islam

When the British formed the basis of their empire in the 1600s by acquiring territories in India and North America, they already had many centuries’ experience of foreign involvement. One of the most remarkable aspects of the force that reshaped Eurasia 1,000 years earlier is that there was no prelude: the Arab conquests, and the Islamic empire that they created, came out of nowhere. By the time of the death of the Prophet Mohammed in 632 most of the tribes of the Arabian peninsula had united under the banner of Islam, some out of faith, others from expediency. But few people outside Arabia knew who Muslims were or worried about the threat they might pose.

There were two significant forces in this part of the 7th-century world: the Byzantines in Constantinople and the Persians on the Tigris river at Ctesiphon, south of Baghdad. These were, as one contemporary chronicler called them, the ‘two eyes of the world’.