The military danger of the Frankish powers was not the worst result of the Crusades on the Byzantine Empire. Even more important was the sapping of its sources of wealth and the decay of its commercial prosperity, as the consequence of the development of the trade of the Italian republics, like Pisa, Genoa, and Venice, who really reaped nearly the whole material advantages of the Crusades. Acre and other Syrian ports began to supersede Constantinople as the great meeting-places of Eastern and Western trade. The skill and energy of the Italian merchants transferred the commerce of the Levant from Greek to Western hands. Since the loss of the rich agricultural districts of Asia Minor, the commerce of Constantinople was the one really solid source of Byzantine prosperity. The revenue of the imperial exchequer now began to fall off, and the disastrous expedients of Alexius to restore it made permanent ruin more certain. In the hope of making the Bosporus and Golden Horn as attractive to the Italian traders as the waters of the Levant, Alexius sought to entice the Venetians back to his ports by giving them exemption from customs dues (1082). The Venetians were established in a special quarter of Constantinople, exempt from the jurisdiction of the Greek authorities, with its Catholic church, its walls, and its magistrates. The Pisans had privileges less extensive but still considerable. Such concessions made the Italians easily able to undersell the native merchants and to establish their factories on an almost independent basis. But it was unlikely that the shrewd Venetians would be content with what they had got. Their settlement within the Empire as traders only paved the way to the time when they aspired to establish themselves as rulers. It was a strange turn to make arbiters of the destiny of the Empire those Venetians who had in former times protected themselves from Western Cæsars by parading their dependence on the Emperor at Constantinople, and whose city bears to this day the abiding impress of Byzantine art. The strong Comnenian Emperors postponed the danger for a time, but when the Empire was again divided between rival claimants, it was as natural to the Venetians as it was to the English and French in India to take advantage of the decay of an ancient but stagnant civilisation to turn from their factories and counting-houses to play the part of conquerors and rulers.