With this increase of wealth and culture in central Europe there came a considerable extension of knowledge and a powerful stimulus to curiosity concerning the remote parts of Asia. The conquering career of Jenghis Khan (1206-1227) had shaken the world to its foundations. In the middle of that century, to adopt Colonel Yule's lively expression, "throughout Asia and eastern Europe, scarcely a dog might bark without Mongol leave, from the borders of Poland and the coast of Cilicia to the Amur and the Yellow Sea." About these portentous Mongols, who had thus in a twinkling overwhelmed China and Russia, and destroyed the Caliphate of Bagdad, there was a refreshing touch of open-minded heathenism. They were barbarians willing to learn. From end to end of Asia the barriers were thrown down. It was a time when Alan chiefs from the Volga served as police in Tunking, and Chinese physicians could be consulted at Tabriz. For about a hundred years China was more accessible than at any period before or since,--more even than to-day; and that country now for the first time became really known to a few Europeans. In the northern provinces of China, shortly before the Mongol deluge, there had reigned a dynasty known as the _Khitai_, and hence China was (and still is) commonly spoken of in central Asia as the country of the Khitai. When this name reached European ears it became _Cathay_, the name by which China was best known in Europe during the next four centuries.[325] In 1245, Friar John of Plano Carpini, a friend and disciple of St. Francis, was sent by Pope Innocent IV. on a missionary errand to the Great Khan, and visited him in his camp at Karakorum in the very depths of Mongolia. In 1253 the king of France, St. Louis, sent another Franciscan monk, Willem de Rubruquis, to Karakorum, on a mission of which the purpose is now not clearly understood. Both these Franciscans were men of shrewd and cultivated minds, especially Rubruquis, whose narrative, "in its rich detail, its vivid pictures, its acuteness of observation and strong good sense ... has few superiors in the whole library of travel."[326] Neither Rubruquis nor Friar John visited China, but they fell in with Chinese folk at Karakorum, and obtained information concerning the geography of eastern Asia far more definite than had ever before been possessed by Europeans. They both describe Cathay as bordering upon an eastern ocean, and this piece of information constituted the first important leap of geographical knowledge to the eastward since the days of Ptolemy, who supposed that beyond the "Seres and Sinae" lay an unknown land of vast extent, "full of reedy and impenetrable swamps."[327] The information gathered by Rubruquis and Friar John indicated that there was an end to the continent of Asia; that, not as a matter of vague speculation, but of positive knowledge, Asia was bounded on the east, just as Europe was bounded on the west, by an ocean.