Thus, for just a century,--from Carpini and Rubruquis to Marignolli,--while China was open to strangers as never before or since, a few Europeans had availed themselves of the opportunity in such wise as to mark the beginning of a new era in the history of geographical knowledge. Though the discoveries of Marco Polo were as yet but imperfectly appreciated, one point, and that the most significant of all, was thoroughly established. It was shown that the continent of Asia did not extend indefinitely eastward, nor was it bounded and barricaded on that side, as Ptolemy had imagined, by vast impenetrable swamps. On the contrary, its eastern shores were perfectly accessible through an open sea, and half a dozen Europeans in Chinese ships had now actually made the voyage between the coast of China and the Persian gulf. Moreover, some hearsay knowledge--enough to provoke curiosity and greed--had been gained of the existence of numerous islands in that far-off eastern ocean, rich in the spices which from time immemorial had formed such an important element in Mediterranean commerce. News, also, had been brought to Europe of the wonderful island kingdom of Japan (Cipango or Zipangu) lying out in that ocean some hundreds of miles beyond the coast of Cathay. These were rich countries, abounding in objects of lucrative traffic. Under the liberal Mongol rule the Oriental trade had increased enough for Europe to feel in many ways its beneficial effects. Now this trade began to be suddenly and severely checked, and while access to the interior of Asia was cut off, European merchants might begin to reflect upon the value of what they were losing, and to consider if there were any feasible method of recovering it. [Sidenote: The accustomed routes of Oriental trade cut off by the Ottoman Turks.] [Sidenote: Necessity for finding an "outside route to the Indies."]