Because I'm the worst and need everything to be organized, I shall say that I would've personally arranged the sets by theme of civilizations. So basically like this.
Set I (Religious) - Jerusalem, Papal State, Tibet
Set II (African) - Mali, Zimbabwe, Ashanti
Set III (New World) - Olmec, Sioux, Cherokee
Set IV (Asian) - Khmer, Qin, Nepal
Set V (Middle East) - Timurids, Durrani, Phoenicia
Set VI (Ancient Kingdoms) - Numidians, Gallia, Hittites
Set VII (Islanders) - Tahiti, Scotland, Haida
Set VIII (Ukrainian Horselords) - Hetmanate, Tatars, Scythia
Set IX (Eastern Europe) - Romania, Bulgaria, Lithuania
Not perfect, of course, Scotland is certainly a bit of an odd duck in any of these really, but I'd do that to give all of the sets a bit more identity and flavor beyond just a number. Of course this is just me talking from my probably OCD-ish perspective ^^;
In any case, it's good that the AI can work the Haida! Hopefully they'll make use of it in a war - it's pretty advantageous to be able to attack a land melee unit and not be prone to counter-attacks.