Temujin (aka Genghis Khan)

Reasons: United the many Central Asian plateau tribes, developed a civilian and military code for the governance of the expanding Mongol Empire that was tolerant of different ethnicities, cultures and religions, administrative advancement based on merit not ethincity or family (except his own family), oversaw the development of a very successful military organizational structure and way of war, and granted a degree of autonomy to his Generals (who were very adaptive in adopting others tactics and technologies in warfare).

Oh, and he created one of world’s largest empires - or maybe that should be fought and marauded his way to - one of world’s largest empires; albeit a rather fleeting one that was split up after his death. His downside was he and his Generals were seriously ruthless.