Genghis Khan : The Man Who Conquered the World

At its peak, his empire stretched from the Pacific Ocean to central Europe, including all of China, the Middle East and Russia. So how did an illiterate nomad from the steppes of Central Asia rise to such colossal power, eclipsing Alexander the Great, Julius caesar and Napoleon ? Credited by some with paving the way for the Renaissance, condemned by others for being the most heinous murderer in history, who was Genghis Khen ?