They created wells deep in the ground in order to pull up water. The wells fill up over time and can sustain villages. Most villages at this time contained one major well and then the village grew around it.
It was the "(1) location on waterways" that was a geographic factor that enabled the cities of <span>Nanjing and Mogadishu to develop into powerful trading centers.</span>
The cause was MAIN -imperialism alliances nationalism and militarism
