They met with initial resistance from the representatives of the Byzantines and Persians. But the two empires were structurally and materially exhausted from long decades of war against one another. Emperors in Constantinople were so short of their own troops that they were forced to recruit the majority of their armies from among the Turks—a new nomadic steppe power that had appeared in the region around the Caspian Sea from the sixth century.18 The Muslims by contrast were battle hardened but not yet battle weary.
