How do the web articles compare with the way Bentley and Ziegler treat the Mongols and the west African Islamic kingdoms of Ghana and Mali?

http://afe.easia.columbia.edu/mongols/index.htm
http://www.bbc.co.uk/worldservice/specials/1624_story_of_africa/page80.shtml
http://www.bbc.co.uk/worldservice/specials/1624_story_of_africa/page82.shtml

Please answer the following questions:

How do the web articles compare with the way Bentley and Ziegler treat the Mongols and the west African Islamic kingdoms of Ghana and Mali?
What might explain the differences in treatment? Which approach do you prefer and why?