Multi-Cultural government, religious tolerance. Support for other countries such as Islam. Food, tools, inventions, and ideas spread along protected trade routes. From China, windmills, gunpowder, playing cards and porcelain moved to Europe.
I don't know specifically but I believe it relates to Pax Mongolica and how they relied on trade with sedentary societies to get products that they themselves could not produce. I also believe that the Mongols helped keep the silk trade routes alive.
