What about the bush people in New Guinea? What about the native Indians of the Americas? What about the eskimos? the aborigines? What about all the people who due to transportation and communication limitations were never affected by the Bible? What about their history? Why should the story of Adam & Eve be THE story, when there are many different versions of history, passed down in many different cultures?
Just playing devils advocate here on this point, but a JW would say, these people only dispersed at the Tower Of Babel incident, when the lanuages were confused. Maybe Jehovah confused their languages by race & genetics and so they dispersed, therefore the history of the people you mention is explainable, it just began after Babel.