In the first years of 13th century, Genghis Khan unified the Mongolian tribes, founding the Mongolian Empire, and led them to conquer nearly all of Asia, Central Asia, Russia and center East. His armies occupied a great element of European countries, too, having a baby to one of the biggest empires ever sold. His cavalry devices, particularly his horse archers, were Genghis Khan's elite troops and were able, with fierce but well coordinated costs, to strike terror within their enemies' hearts.