Well all civilaizations have religion and it has taken advantage of religion as a way to claim that their power is God given or their divine right. It has had many influences on many different people from the world
Also the economy is important, too. Trading and exporting man made items and agriculture was a way of making money and introducing new foods, cloths, etc. Cultural diffusion
Also a river is important to explore after all the four main cradles of civilization were started near Rivers. (Egypt, India, China and Iraq)
