Oh, probably. Different groups will probably ride vastly different animals because of necessity.Could one, or more, of the minor Kyrani tribes ride something other than horses? Need not be a power-breaker as they will be smaller in numbers. Flightless birds spring to mind, or giant goats for a tribe dwelling nearer mountains?
Yes. Absolutely.I always liked the phrase, “spider-haunted” in REH stories. With your mythology, it could be an actual thing in a ruinous city of undead spiders, solifugids etc?
I'm sold. This is now a canonical magic item.Magic Item
Crowned cowl of Buvalu
Unique, Magical Headgear
This large linen cowl is toped with a tattered, almost ironically small crown made of copper. No gems nor engraved precious metals adorn the crown. Yet, it is the lost crown of the first dynast-king of Achelb, the mighty thief Buvalu. While coiffed and attuned to the crown, you gain the following benefits:
- You have Advantage on all History or Investigation checks made to find or identify valuables worth more than 150 gp.
- You are considered Large sized for the purpose of carrying load.
- Any retainers of yours can use their special ability one more time per day.*
* I dont recall exactly how retainers work in LU so it could be something like advantage on Moral test or extra starting Loyalty.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.