We must now turn back and briefly sum up the additions to knowledge made by travellers, pilgrims, and merchants, and recorded in literary shape in the form of travels. [_Authorities:_ Lelewel, _Géographie du Moyen Age_, 4 vols. and atlas, 1852; C. R. Beazley, _Dawn of Geography_, 1897, and Introduction to _Prince Henry the Navigator_, 1895; Nordenskiold, _Periplus_, 1897.] CHAPTER IV MEDIÆVAL TRAVELS In the Middle Ages--that is, in the thousand years between the irruption of the barbarians into the Roman Empire in the fifth century and the discovery of the New World in the fifteenth--the chief stages of history which affect the extension of men's knowledge of the world were: the voyages of the Vikings in the eighth and ninth centuries, to which we have already referred; the Crusades, in the twelfth and thirteenth centuries; and the growth of the Mongol Empire in the thirteenth and fourteenth centuries. The extra knowledge obtained by the Vikings did not penetrate to the rest of Europe; that brought by the Crusades, and their predecessors, the many pilgrimages to the Holy Land, only restored to Western Europe the knowledge already stored up in classical antiquity; but the effect of the extension of the Mongol Empire was of more wide-reaching importance, and resulted in the addition of knowledge about Eastern Asia which was not possessed by the Romans, and has only been surpassed in modern times during the present century. Towards the beginning of the thirteenth century, Chinchiz Khan, leader of a small Tatar tribe, conquered most of Central and Eastern Asia, including China. Under his son, Okkodai, these Mongol Tatars turned from China to the West, conquered Armenia, and one of the Mongol generals, named Batu, ravaged South Russia and Poland, and captured Buda-Pest, 1241. It seemed as if the prophesied end of the world had come, and the mighty nations Gog and Magog had at last burst forth to fulfil the prophetic words. But Okkodai died suddenly, and these armies were recalled. Universal terror seized Europe, and the Pope, as the head of Christendom, determined to send ambassadors to the Great Khan, to ascertain his real intentions. He sent a friar named John of Planocarpini, from Lyons, in 1245, to the camp of Batu (on the Volga), who passed him on to the court of the Great Khan at Karakorum, the capital of his empire, of which only the slightest trace is now left on the left bank of the Orkhon, some hundred miles south of Lake Baikal.