"During the 13th century, he conquered most of civilization with an army of fewer than 100,000 Mongol horsemen. "
by terrorizing civilized peoples, raping women, burning villages. He WAS a terrorist!!
Besides, did the Mongols succeed in leaving their "civilization" behind in the conquered territories? Where are they today? Except in their intellectual off-spring such as Osama.
The author is trying to make a point, but this is NOT a good analogy!
Khan's army was notoriously brutal. In fact Rome fell in part beacuse after losing a first battle in horrible way - the stories that spread made it impossible to recruit another decent army - since all were citizen soldiers.
It is an excellent analogy. What civilization do you expect OBL to leave behind?