7. Zenith of Mongol Empire
Genghis was succeeded by his son, Ogedei, who was not his father’s military equal, but who was wise enough to know that he was not. From his capital in Mongolia, Ogedei directed simultaneous campaigns on multiple fronts that were separated by thousands of miles. He entrusted their execution to his father’s capable generals, whom he authorized to act independently within their theaters, subject to Ogedei’s orders, which were relayed via a swift horse relay communications network. By the time Ogedei died in 1241, the empire had reached its furthest southward extent, into southeast Asia, and westward all the way to the outskirts of Vienna.