A prelude to the Age of Discovery was a series of European expeditions crossing Eurasia by land in the late Middle Ages. Although the Mongols had threatened Europe with pillage and destruction, Mongol states also unified much of Eurasia and, from 1206 on, the "Pax Mongolica" allowed safe trade routes and communication lines stretching from the Middle East to China. A series of Europeans took advantage of these to explore eastwards. Most were Italians, as trade between Europe and the Middle East was controlled mainly by the Maritime republics. The close Italian links to the Levant raised great curiosity and commercial interest in countries which lay further east.