As mentioned by many reviewers, this book has a lot of preaching about the invalidity of the concept of races.
What interests me to the book was the title "Mapping Human History". 10% of this book content is in this area, and if those content are condensed into a short paper, it'd make really good reading.
The whole book is a quick read. The key "mapping" can be summarized as follows:
1. "Out of Africa" hypothesis (sole source of modern homo sapiens is from Africa) is affirmed by genetic research.
2. First wave out of Africa (~65,000 years ago) is by sea along Arabian peninsula to Indian Ocean which has two streams afterwards, one earlier stream down Oceania and a later stream up East Asia.
3. "Mongoloid" characteristics are formed relatively late (~20,000 years ago? I don't recall anymore)
4. Second wave is through Sinai peninsula by land ~45,000 years ago and completely displaced Neaderthals in Middle East & Europe by around ~30,000 years ago
5. First wave and second wave met in (north) Central Asia from different directions
6. Primarily the East Asia stream entered the Americas ~15,000 years ago (but could be earlier), though some genes from the ME/Europe stream have also entered (because of 5.)
7. All these really happenned before the invention of agriculture (and culture). Agriculture (and potentially other key technologies such as use of iron) privileges the groups who are the first to under-go population explosion. A lot of racial mixing especially on the fringes afterwards. This is where Jared Diamond's "Guns, Germs and Steel" picked up.
If you're just interested in the mapping, you don't need to buy the book-- save it for something else.