We learn from Marco Polo that, in the administration of his empire, Kublai Khan made use of a fast and simple message system. Horse riders spaced every 40 kilometers allowed messages to cover 500 kilometers a day Marco also learned the secret of asbestos cloth, is made from a mineral and doesn't catch fire. Paper money also took him by surprise, as it was not yet in use in the West at that time. Homes were heated with "black stones which burn like logs." Those stones were coal- unknown in most of Europe and they were so plentiful that many people had a hot bath three times a week.