In the first years of 13th century, Genghis Khan unified the Mongolian tribes, founding the Mongolian Empire, and led them to conquer most of China, Central Asia, Russia and Middle East. His armies occupied a good part of Europe, too, giving birth to one of the biggest empires in history. His cavalry units, especially his horse archers, were Genghis Khan's elite troops and were able, with fierce but well coordinated charges, to strike terror into their enemies' hearts.