Nope, not a problem. I'd probably consider "antiquity" in Iran to last until the Muslim conquest. In the West, it was the German conquests, maybe even until Constantinople finally lost Rome. 

Maybe read the discussion:) we are trying to figure out what they will do. Just kinda different types of civs that have things in common. And eventually it will be more clear tribals are better/most suited for X, city states are better/most suited for Y

I haven't read all of the current discusion, but what do these "groupings" do? Is there like a teambonus if I have an ally who is in the same group?

Spartans have a further limit on their champions which have excellent stats already. It does not have to be a hard limit, one idea is to have it as a percentage of current population. we actually did the opposite. There is no restriction on their champs… yes they are strong…. But champs can’t gather resources to produce more champs  you can only train 3 helots per every champ…. Although you can train up to 10 without. i dont know how to do a percentage of population….. we also have it so spartiates take longer and longer to train as you phase up and tech up. So you need to mix in more helots and Perioikoi 

In one of our versions we had a bonus where CS for Brit’s/gauls and more HP. Cause where they bigger/fiercer in stature say compared to the Romans?  maybe I’m just thinking too much American dramatized Vikings on TV  but could do something similar if it could fit for the tribes. All melee + 25 health or something.