the recovery in July 1099 of the city of Jerusalem by crusaders after four and a half centuries of Muslim rule was the strongest indication yet of a shift in the balance of power from the eastern Mediterranean region to the west. The Balkans and the Levant were in no state to take advantage of beneficial economic forces which were just as much at work in them as in western Europe. The Byzantine empire had been gravely damaged by the occupation of most of Asia Minor by nomadic Turks, although, in a situation reminiscent of the barbarian incursions of the third century, rebellious ‘Roman’ generals had to a large extent brought this on themselves by inviting the Turks in as mercenaries. The empire had no more than a shadow of a presence in central Greece and the Balkans and it suffered from the fact that it had never had great trading or industrial sectors which could have helped to compensate for its territorial losses: Constantinople had been at best a great consumer city. Profitable commercial centres needed to be on trade routes rather than at the end of them and when he encouraged Venetian and Pisan merchants to come to Constantinople the emperor Alexios I may have been trying to create the vital extra overseas leg that an international market of this kind would need.