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 worlds population is growing and is overpopulating. This is negatively affecting the worlds biodiversity.
This is important, because this lead to more trade routs with other countries, and this strengthen the empire as a whole. These roads also lead to more connections to cities, and lead to more homes, and overall improved their society as a whole.
Many people consider fear to be the most influential factor in Mitchell Palmer's campaign.