Humanity has begun to scavage and create new technology with the resources of old. The previous era of humanity mined everything and consumed it. While significant amounts of the previous era have been lost to time, the desert planet of Terra is full of ruins, junk yards and other remenants of the consumerist era of old. After being pushed to near exinction, humanity's numbers have slowly recovered, and over the last couple of hundred years parts of mankind have begun to transition to an agrarian civilization, using what remains of the civilization of yore to spur a new greener era in the desert.
It was several thousand years ago when man was reduced to ash. It has been nearly 4000 years since then. Humanity was reduced down to numbers in the tens of thousand. Global communication was lost. Everything reverted. Not much is known about the before times. The average person in the world knows basically nothing about the before times. Scholars, archeologists, magicians, and other specialized persons might know a few things about the before times, but they know about as much as the people in the 1600s new about ancient mesotampia.
The Geolithic revolution began around several hundred years ago, and has been slowly growing ever since. Only in the last few hundred years have small cities grown from large villages. The ability to harness the resources left behind from the previous era are akin to magick. People who understand the