I used to wonder how did the Islamic Golden Age end, how did the Muslim World go from leader in science, technology and commerce to has-been. Now I see leaders in the West destroying in years what took centuries to build. Civilizations like living organisms go through cycles of birth, rise, peak, stagnation and decline, some make a comeback in a different form like Europe after the Renaissance and China after Communism, and some don’t. Good thing we have other nations picking up after the decline of Western Civilization.
So that’s why regions near the equator tend to be more populous.