User blog comment:Withersoul/How would man have fought against the grim before using dust?/@comment-16763585-20130902152013

Perhaps humans acted back then as the Grimm do today. They would hide in the corners of the world in small packs, staying away from the Grimm until they saw the oppritunity to strike. A Grimm might wander too far away from the pack and would be ambushed by the humans for example. It was only once humans discovered Dust that they could start taking control of nature and being more aggressive against the Grimm, eventually collecting together into the collective society that exists at this day and age.

As for the great war, maybe the Grimm took one final stand before their organized resistance was broken and they were forced to flee into the shadows.