Saudi Arabia because f those guys
Well from what I know they did use obsidian, they did live in large numbers and did take shelter in the highlands. Hope this helps
The AG industry was able to provide way bigger amounts of food. With higher amounts and productivity gave farmers a easier time to keep up with the growing population around the world. more people means higher demand for food in larger quantities.
Jamestown experienced a drought from 1606 to 1612
Enslave the Natives. That is a big one.