The evidence is growing that in essence the first settlements we can call civilization were actually just functions of wherever the population density was greatest. The Indus Valley, the valley of the Nile and the confluence of the Tigris and the Euphrates are of course areas where many many people have settled just in historical times. The Russian Steppes have been a transit point between Asia and Europe and so forth. In Europe our earliest evidence of cities comes from the shores of lakes, and the corpse of the murdered Otzi who was associated with at least one of these lakeside communities. As we entered the bronze and iron ages, and the population grew we began to see evidence of forts -- people had to defend themselves against each other.
Civilization grew out of our attempts to keep order as we met strangers for the first time. It grew simply out of their being more of us and this is how, to this day, it has progressed.
