Let’s talk possible paths:
Barbarian: Civs like the Alans, Tuyuhan, Vandals and Saka mean a world wide reach. You could even have the Chichemeca as new world Barbarians and get Eagles more love!!
Issues: you need a likely Shareable barbarian Type of raider or regional unit and boy deciding the hard line of raiding/barbarian civ is hard. Are Franks, Teutons and Burgundians when they spent their first few centuries doing just that to Rome or attacking Arabic caravans in the Crusades? Are Turks for Seljuk? Are the Jurchens whom eventually settled? Are Saracens who help rapid spread a religion with razing?
What would this unit be? If it’s infantry then sure it could be slapped into any raiding civ including American and southern African, but what would it do?
Is it cavalry? Perhaps it’s a scout type of plunder unit who at the stable you can toggle between food, wood and captive where after killing or assisting enough kills with the unit your next villager queued is free and instant. This is probably a bit easier to implement if the stats don’t deviate too much from the scoutline except maybe building killing power, and might help the Mapuche have a real excuse to even have a stable and some horse techs for the one unit that makes sense there!
Is it nothing? This sort of expansion could easily fall into the old Conqs style more easily than any other expansion to date! Chich can be your new Eagle civ. Alans are your new Caucuses civ with Steppe Lancer and Camel and Dromon. Vandals are a strange breed with likely MXbow to remind you they are European to go with their camels and strong Dromon infused navy.
Tuyuhan revisit some of the 3k as Hei Guang and Xianbe riders fit in pretty well!
Saka are interesting because their reach is from steppes and down into parts of Northern India so inject those non horse mounted units directly into my tech tree!!!
So this seems like a safe one since it doesn’t really need any new buildings or regionals unless you want to show off.
Next is West Africa . I mean the northern part. Salt and gold aplenty. Civs with a focus on camels. This expansion almost begs for a Berber rework since many of these civs had something akin to a javelin horseman and rode plenty of camels enough that they might have archers. Speaking of archers most of theirs used venom from the rare desert flowers instead of crossbows and quilted Lifidi armor wasn’t uncommon on certain horsemen.
As you can see this area looks like fun but I don’t drink enough alcohol to figure how to make it all work so well especially not by my lonesome.
Also probably a regional Mining Camp. Auto gathering from nodes seems impossible but the very tiniest trickle? For 150w 3g/1.5s per minute means you get all of 150g after 50 minutes if your game lasts that long.
Steppes: Steppes are easy enough and more of that Central Asian stuff for Persians to not have. Lancers and some of the more southern towards India would have elephants and those towards China would have rocket things! I’m all in on it! Probably don’t need a new region unit.
Mexico! Eagles are a classic and ignored step child that’s better than your actual child and you know it but you can’t admit it. To compare to southern America some new regional likely a skirm replacement might be needed. This area can bleed into some Center more and Spurherj civs with some having both regional scouts and us as a team will go into political levels of violence deciding which civ gets which of Eagle or Champi as the scout and I don’t know the correct answer
Anyway this is where we stand. Let’s make a choice!
I’m leaning towards the Barbarians with no shared raider or plunderer but that seems cowardly for a big crafter like us to do
If we have the talent to show off we go all ham with a big African packet
There’s also the harrowing fear of what civs do we replace