There have been eight previous worlds.
You may refer to them as ages, aeons, epochs, or eras, but it’s not wrong to think of each as its own individual world. Each former world stretched across vast millennia of time. Each played host to a race whose civilizations rose to supremacy but eventually died or scattered, disappeared or transcended. During the time that each world flourished, those that ruled it spoke to the stars, reengineered their physical bodies, and mastered form and essence, all in their own unique ways.
Each left behind remnants.
The Ninth World is built on the bones of the previous eight, and in particular the last four. Reach into the dust, and you’ll find that each particle has been worked, manufactured, or grown, and then ground back into drit—a fine, artificial soil—by the relentless power of time. Look to the horizon—is that a mountain, or part of an impossible monument to the forgotten emperor of a lost people? Feel that subtle vibration beneath your feet and know that ancient engines—vast machines the size of kingdoms—still operate in the bowels of the earth.
The Ninth World is about discovering the wonders of the worlds that came before it, not for their own sake, but as the means to improve the present and build a future.