More than 3,000 years ago a mysterious and ruthless civilization rose from nothing, created a brutal and unstoppable army and built an empire that rivalled Egypt and Babylon. Yet, just as it was at the height of its powers, the great empire suddenly vanished from history.

Lost Cities of the Ancients 3 The Dark Lords of Hattusha. 
http://youtu.be/T7U-b2rdtwQ