Beginning in 1206 with the unification of the Mongol tribes under Genghis Khan, the Mongol conquests created the largest contiguous land empire in history, stretching from Korea to Hungary by the late 13th century. Highly mobile cavalry armies overran much of Eurasia, and the empire was later divided among successors into khanates. Conquest could be devastating to cities that resisted, most notoriously the sack of Baghdad in 1258, which destroyed the Abbasid capital and its libraries. Yet under the resulting stability, the Pax Mongolica, long-distance trade and travel flourished.
The conquests integrated Eurasian trade, technology and ideas along the Silk Road, easing exchange between East and West. At the same time the destruction of cities such as Baghdad ended long-standing urban and intellectual centres.