He has been criticized for being an environmental determinist and for not incorporating a more inclusive theory with room for cultural autonomy. Although these criticism are valid, I have yet to read a book that both explains the emergence of Eurasian city-state networks and the lack of development elsewhere. In the future, I hope that someone can adequately build on what he has done. As far as him not being a credible source in anthropology, I can say that most people in my department have nothing but positive things to say about this work. If I have a major criticism, it may be that it is too simplistic and does not focus enough (or at all) on the environmental factors that led to European colonial expansion. Either way, it is on my list because of what it taught me at a key point in my academic trajectory.