The lifestyle of the mongol people in the middles ages can best be described as a. civilized. b. nomadic. c. city living. d. agricultural.

The Mongolians where nomadic they lived off the land  and they wondered  so B. would be your answer 

They were often know as nomadic

So your answer is B. Nomadic

Hope this helps

It is useful for historians to write narratives so that history can be passed on from their point of view.  think about a story being told in third person, then think about it again being told in first person, by someone who actually experienced the event.