In the 7th and 8th centuries AD, armies inspired by the new religion of Islam burst out of Arabia to subjugate the Levant, southwest Asia, North Africa and the Iberian peninsula. These Arab conquests followed immediately after the Prophet Mohammed's death in 632. By this time, against all the odds, he had managed to unite the feuding tribes of Arabia at the point of his sword.
The Muslim conquests lasted until 750, by which time several generations of marauding Arab armies had carved out an Islamic empire (the Umayyad empire, centred on Baghdad) which, in size and population, rivalled that of Rome at its zenith, extending from the shores of the Atlantic in the west to the snow-bounds mountains of Central Asia and the borders of China in the east. In the process they had completely crushed one great empire (the old empire of Byzantium), and hollowed out another (that of the Iranian Sassanids). The Arab Conquests represent one of the greatest feats of arms in history and utterly changed the world.
Justin Marozzi, much-praised author of The Man Who Invented History and Baghdad: City of Peace, City of Blood, tells their story with unfailing narrative verve and deep scholarly authority.