Rubruquis was sent, about this time, by the king of France to the Mogul emperor:  he passed through the Crimea, and along the shores of the Volga and the Caspian Sea; visited the Khans Sartach and Batou; and at length arrived at the great camp of the Moguls.  Here he saw Chinese ambassadors; from whom, and certain documents which he found among the Moguls, he learnt many particulars respecting the north of China, the most curious of which is his accurate description of the Chinese language and characters.  He returned by the same route by which he went.  In his travels we meet with some information respecting the trade of Asia.  The Mogul khans derived a considerable revenue from the salt of the Crimea.  The alum of Caramonia was a great object of traffic.  He is the first author, after Ammianus Marcellinus, who mentions rhubarb as an article of medicine and commerce.  Among the Moguls he found a great number of Europeans, who had been taken prisoners:  they were usually employed in working the mines, and in various manufactures.  He is the first traveller who mentions koumis and arrack; and he gives a very particular and accurate description of the cattle of Thibet, and the wild and fleet asses of the plains of Asia.  Geography is indebted to him for correcting the error of the ancients, which prevailed till his time, that the Caspian joined the Northern Ocean:  he expressly represents it as a great inland sea,—­the description given of it by Herodotus, but which was overlooked or disbelieved by all the other ancient geographers.

While the pope and the French monarch were thus endeavouring to conciliate the Moguls by embassies, the Emperor Frederic of Germany, having recovered Jerusalem, Tyre, and Sidon, formed an alliance with the princes of the East; and this alliance he took advantage of for the purposes of oriental commerce:  for his merchants and factors travelled as far as India.  In the last year of his reign, twelve camels, laden with gold and silver, the produce of his trade with the East, arrived in his dominions.  The part of India to which he traded, and the route which was pursued, are not recorded.

Among the most celebrated travellers of the middle ages, was Marco Polo:  he, his father, and uncle, after trading for some time in many of the commercial and opulent cities of Lesser Asia, reached the more eastern parts of that continent, as far as the court of the great khan, on the borders of China.  For 26 years they were either engaged in mercantile transactions, or employed in negociations with the neighbouring states by the khan; they were thus enabled to see much, and to collect much important information, the result of which was drawn up by Marco Polo.  He was the first European who reached China, India beyond the Ganges, and the greater number of the islands in the Indian Ocean.  He describes Japan from the accounts of others:  notices great and little Java, supposed to be Borneo and Sumatra; and is the first who mentions