Around 1200, Genghis Chan united the Mongols, and established an empire that was to become the largest one the world has ever known, spanning the larger part of Asia, from Korea to Mesopotamia. Genghis's son Ogotai also threatened the countries of Europe: In 1238-1241 a Mongol invasion force conquered Russia and reached to Poland, Silesia and Hungary. Then they suddenly turned around: Ogotai had died, and a new Chan had to be chosen. But the Christian nations of Europe had learned of the power of the Mongols, and feared that they would come back.
When in 1243 Innocentius IV was elected pope, he sent out an envoy to the Mongols to ask them not to attack the Christian lands. This envoy was Giovanni de Piano Carpini. He left his monastery in 1245, and the next year he reached the Mongol court in Syra Orda, just outside the capital Karakoram. He met the new emperor Kuyuk Khan. Kuyuk Khan did not make any promises, but Carpini made useful observations about the Mongols, their habits, country and history.
Some years later, the European attitude towards the Mongols began to change: might they perhaps become allies in the fight against the Muslims in the Middle East? Louis IX, just landed on Cyprus to start the seventh crusade, received a Mongol envoy with just that offer, and a hint that the Chan might be converted to Christianity, in 1248. An envoy, Andrew of Longjumeau, was sent back to the Mongols, but was not received friendly: Kuyuk had died, and the empress-regent demanded tribute in exchange for peace. Nevertheless, a further envoy was sent to the Mongols, the Franciscan monk William of Rubruck. Like Carpini, he did not succeed in getting any Mongol promises of non-agression, but he did write an important report of his voyages and the Mongols.
Although the Mongol empire formed a threat for Europe, it also formed a possibility, especially for the traders. The pax mongolica gave them the opportunity to safely travel through large parts of Asia, all the way to China if wanted. Among the first traders to use this possibility were two Venetian brothers, Niccolò and Maffeo Polo. They had travelled first to Constantinople (Istanbul), then, in 1261, to Sudak on the Crimea. Not finding the trading possibilities they had hoped for, they travelled on to Sarai, a trading city on the Volga, in Mongol territory. Trade was succesful here, but a fight between two different Mongol Chans made it too dangerous for them to return where they came, so instead they traveled on, first to Bulgar, then to Bukhara. There they joined a caravan for Cambaluc, the Mongol capital in China, where they met Kublai Khan. The khan received them cordially, and asked them to return to Europe to ask the pope to send a large embassy of "wise men" to China.
In 1271, the Polo brothers set out for China again. They did not have the 100 wise men, but they had a number of presents from the pope, and Nicolò's son Marco. By way of Mesopotamia, Persia and Central Asia, they travelled to Cambaluc. There they remained for 17 years. Marco became an official for the Chan and travelled through the land. The Polos returned to Persia by sea, and in 1295 finally returned to Venice. Later, Marco Polo was taken prisoner-of-war in a war between Venice and Genova. In prison, he told his adventures to the writer Rusticello, and together they created The Book of Marco Polo. This book became the most important source of information about Asia in the centuries that followed, and a guide for explorers like Columbus.
In the next 50 years, more European traders travelled to China; however, none of them left us a report of his adventures like Marco Polo had done, and we know little about these traders. One European visitor that we know more about is John of Montecorvino. He left for China in 1291 to do missionary work. In India he stayed one year, visited the grave of St. Thomas and made a number of converts, and in 1294 he arrived in China. Again he made some converts, and he was rewarded by the pope with the title of archbishop of Cambaluc.
The first after Marco Polo who wrote a report of his voyages in Asia, was another missionary, Odoric of Pordenone. He left Europe in 1318, travelled to China by sea, visiting India, Sumatra, Java and Borneo, and returned by land. As far as known he was the first European to visit Tibet.
The last medieval voyager to China that we have a name of was again a missionary. His name was John of Marignolli, and he was in China from 1342 to 1346. The Italian traders visited China for the last time around the same period. The Mongol empire was falling apart, and with it the possibility of safe travel throughout Asia. In 1368, the Mongols were driven out of China and the indigenous Ming dynasty took power.