The Tribalverses. These are the universes in which various progressions and events have led to the world of "now" (2010's) being a world of lush forest and primitive technology.
In these universes there have been histories as vast as ours, yet different events have occurred.
Such as in Tribalverse-0001 where the first agricultural revolution (which in our world was around 10,000 - 15,000 years ago) didn't happen.
Or in Tribalverse-2067 where a war in 16th century with no dark age led to a terraforming incident and turned the world lush, and the survivors into tribes...
Many more places and events changed that led the world to this. see below for more.