I think Elijah mentioned this book somewhere. I can’t find where.
The basic idea of the book is to write a history book that does take known population differences into account. Normal history books don’t do that. Generally, the chapters are only very broad sketches of some period or pattern. Much of it is plausible but not too well-argued. If one looks in the references for sources given, one can see that a large number of them are to some 1985 edition of Encyclopedia Britannica. Very odd. This is a post-Wikipedia age, folks. Finding primary literature on some topic is really easy. Just search Wikipedia, read its sources. The book is certainly flawed due to the inadequate referencing of claims. Many claims that need references don’t have any either.
On the positive side, there are some interesting ideas in it. The simulations of population IQ’s in different regions is clearly a necessary beginning of a hard task.
Probably you should only read this book if you are interested in history, population genetics and differential psychology beyond a pop science superficial level.
The author is an interesting fellow. http://en.wikipedia.org/wiki/Michael_H._Hart