Well, an article called "history of Africa" should be an article about the history of Africa. It shouldn't be a link page, I think; we certainly should have an article about the history of Africa on this page. It probably shouldn't be on an "outline of the history of Africa" page, because one goes to a "history of Africa" page precisely to get an outline of the history of Africa.
- To link to a topic that doesn't have an obvious focus within one of the regions below, create a link here at the top level and/or link it within multiple region pages.
In a certain way, there is really no such thing as a "top-level" page within Wikipedia. Pages can and should be linked to from a wide variety of other relevant pages.
Anyway, this sort of thing goes without saying on Wikipedia. We want to interlink pages as much as possible--more or less.
An article about "history of Africa" could be a) very big b) an outline c) a link page.
a) is not good I think, since you can't easy link into a big page. You suggest b) which is ok.
But I think the regions should be left as a separate page and linked at the beginning of the article.