Marco, according to the sinologist Ulrich Neininger (Ulrich Neininger, The Legend of the Venetian Knight-Errant at the Court of Kublai Khan, and the True Story of the Busy Official Marco Polo, how he Grew Rich in China and what he Kept Secret from his Readers, http://ulrichneininger.de/?p=2532), became friends with Zufficar, an official in the Imperial Bureau of Mines. Zufficar, who must have been impressed by the scientific talent of the young man (The historical geographer Berthold Laufer mentions Marco’s “keen power of observation and his large share of common sense” (Berthold Laufer, Asbestos and Salamander. An Essay in Chinese and Hellenistic Folk-Lore, in B. Laufer, Sino-Tibetan Studies. Selected Papers on the Art, Folklore, History, Linguistics and Prehistory of Sciences in China and Tibet, ed. Helmut Walravens, vol. 1 p. 253 (333), p. 245), obviously recommended him for a position with the salt distribution agency. Collecting the salt-tax, the agency was a kind of second tax-office, and tax-officials, under Mongol rule, were often foreigners. (Valentin Gitermann, Geschichte Rußlands, vol. 1, Frankfurt 1965, p. 98.) Marco’s travel routes within China follow the salt springs in the West and the saline areas in the East. His professional experience resulted in ample descriptions of salt-production and salt-trade in his book. Marco returned as a rich man to Venice. Kublai Khan, he maintains, “had presented him with many rubies and gems of great value.” According to Neininger: “An Emperor who presents his officials a box well filled with emeralds and rubies exists only in Rustichellos chivalric romances. Officials at the salt administration usually won a fortune because they embezzled a considerable part of the duties and taxes.” Foreseeable he got at one point of his career in serious troubles. At that time he decided to leave China. “The Lords became somehow envious”, he remarks, and so he thought of an honorable departure, “as he was fearful that the Lords in the long run would not tolerate him.” (Das puch des edeln Ritters vnd landtfarers Marcho Polo, ed. Friedrich Creußner, Nuremberg 1477, p.16.) Only once Marco talks about his profession, stating that he served three years in Yangzhou. The city was then the headquarters of the salt distribution agency. According to Ramusio’s edition, he served there as governor. However an earlier German edition states clearly: “I, Marco Polo, ordered by my master, the great Khan, was three years in the service of the governor and captain of the land Mangi.” (Das puch des edeln Ritters vnd landtfarers Marcho Polo, ed. Friedrich Creußner, Nuremberg 1477, p. 85.) He had taken a typical Chinese officials career where dislocations in three-year intervals were the norm. Definetely, Marco Polo was a tax official. But why did he never tell his readers about it? The reason was, that in the European Middle Ages tax collector was considered a dishonourable profession. (Evamaria Engel, Frank-Dietrich Jacob, Städtisches Leben im Mittelalter: Schriftquellen und Bildzeugnisse, Köln 2006, p. 293.) Secondly, there was the influence of Rustichello who needed for his text a glorious knight in Kublai Khan’s services and by no means a middle level civil servant.