This completely ignores many of the major empires in history. The Roman Empire, the Greek Empire, Babylon, the Egyptian empire, the Persian empire, all were in

This completely ignores many of the major empires in history. The Roman Empire, the Greek Empire, Babylon, the Egyptian empire, the Persian empire, all were in relatively hot weather. Needless to say some of these empire are famous for studying and thinking (e.g. Ancient Greece?).