1295 In 1271, at just 17, Marco Polo (1254-1324) set off on an adventure that would make him legendary. He left Venice with his father, Niccolo, and his uncle, Maffeo, who had previously been to the Far East. After four years and 7,500 miles, the trio reached Shang-du, the summer home of the Mongol ruler Kublai Khan. Kublai Khan (1215-1294), the grandson of Genghis, had come to power in 1260 in Mongolia. When Marco Polo arrived at Shang-du, the Khan welcomed him as a friend. He spent seven years in Khan's court, during which time he was sent on several diplomatic missions. When Marco Polo returned to Venice 24 years later, he was apparently unrecognizable—dressed in rags and behaving in a foreign manner. Still, all of Venice rushed to hear Marco's tales of adventure. His book, The Description of the World—published in 1300, five years after his return—relates many fantastic stories (some untrue) and was translated into several European languages, allowing readers to travel by armchair to exotic places on the other side of the world. Marco also brought back practical information that immediately caught on, such as using coal to fuel fires. More significantly was the use of paper currency, inspired by the Khan's currency, which was invented in A.D. 105 and made of mulberry bark paper. Paper currency would soon become the common currency of Europe.