Introduction

Most of these cultures are centered around OACs or narrow river valleys The Tigris and the Euphrates in many places the entire coastal plain is less than 10 miles thick. It wasn't until the 1900s when you could introduce things like artificial fertilizer That you really got a very dense population footprint even within that zone. This is an area that was among the last parts of the world to enter the industrial era And so you had kind of a classic pyramidal formation for the population density until relatively recently in their history.