I was sitting here thinking about this. I may be wrong tried to look up my facts but I have jetlag out my face. Had a 13 hour flight from Tokyo to Minnesota today.
So, Felarya has properties in the soil that cause cuts, injuries to heal, depending on the severity, overnight. No sickness, and living until you die due to not aging from the soil.
If this is true then most people in cities like Nagev are over 160+ cause if they don't leave they don't die. I could see people longing for adventure and leaving. But if you just stayed there you don't grow in appearance past age 25? How come the population, mostly smart, overran the city to overflowing?
I was also curious on this view. Somebody talked about how humans would go to war with giant nagas, harpies, etc. That giant eye thing that zap everything like a giant death star. Why not build more of them, put them on tanks, or build a fence of them and take over half the continent?
Anyway these were just some thought bunnies I had. Not sure if they have been covered at all.
-T