The inability to travel into the twilisphere is evolutionary, like the inability of penguins to live in the Sahara. When life made its way up the mountains it eventually became specialized to live in that habitat. Humans (ish...things...) evolved from said life. Because humans can't cross the twilisphere, they were confined for most of their history to a single tight cluster of mountain peaks later called the Imperial Continent.
No humans existed on other peaks prior to steam powered (or hand powered in earlier years) colonization because convergent evolution does not work that way. The land animals on each peak are all naturally endemic; however many plant species can be found on multiple peaks due to airborne seed spread or transmission of gametes by long distance flying creatures. As a result of the universal latitude-based plant life, land creatures on separated peaks are often similar due to convergent evolution, though physiologically different (compare sharks to dolphins).
The second half of the historical background is wrong on many levels.
If you're going to be entering this contest, it helps to have more than basic understanding of evolutionary biology.
I know this world inside and out; if you're entering this contest and have any questions about technology, zoology, sociology etc. as it pertains to AE's past, send me a PM and I can clarify things.
Timmon26
Matt joined
I'm a concept artist specializing in vehicle design. I design the units and vehicles for the upcoming game Aero Empire, and I regularly submit concepts to the indie project Infinity: The Quest for Earth...