The incentive to reduce cost of transportation was as strong in those days as it is at present. The northern route being mainly overland was a source of incessant worry to the trader. The unrest which followed the appearance of Mohammedanism, the reluctance of the adherents of Islam to deal with infidels, rendered commerce more and more risky. Transportation by land was slower and less profitable than by sea, as it is now. Caravans could not avoid brigands as easily as ships could escape pirates. It was not only a case of argosies reaching port but also of camels escaping highwaymen. In addition, duties had to be paid at four or five different points of transshipment. If we examine the pepper and ginger trade alone--the supply of both of which came from the east--we find that from Calicut, the great emporium of trade on the Malabar coast, these spices were carried by the Arabs to Jiddah and thence to Tor, on the Sinaitic peninsula. Overland journeys began at the last point and extended to Cairo. From the city a river journey on the Nile to Rosetta followed, after which the freight was packed on camels and sent to Alexandria. All these conditions made for the increase of cost of the eastern wares which were supplied to Europe. With the cost of eastern commodities rising higher and higher, as land transportation became more and more hazardous, the minds of navigators naturally turned to the possibility of discovering a sea-way to India and Cathay. The discovery of America in the course of these endeavors to lower prevailing freight rates was an inevitable consequence of economic conditions. The chief point of interest resides in the fact that the discovery which immortalized Columbus’ name was accelerated by fully half a century through the falling of Constantinople into the hands of the Turks in 1453. The capture of the Byzantine capital came as the death-blow to an already declining commercial intercourse. Henceforth the Moslem was to stand guard at the western gate through which east-to-west intercontinental trade had passed; and there seemed to be no doubt that he was firmly resolved to prevent the Christian from traveling back and forth through his dominions. It meant the definite closing of the western gate to eastern commerce. The first evil effects of the Turkish conquest were felt by the Venetians and Genoese. The Venetians especially incurred the wrath of Mohammed the Conqueror on account of the aid they had rendered to the beleaguered capital. Greater leniency was shown by the Turks to the Genoese, who had refrained from open manifestations of sympathy with the Byzantines.