That was from the base game. In all the expansions the natives were far more widely used.
They’re prioritizing factions that give the most bang for their buck and can be used widely. It also helps for recognizability if the factions are on lots of maps and you encounter them often enough to be familiar. It would be hard to keep track of all the natives if there were tons on just a few maps.
I’ve suggested adding Tartary and Baikal to break up Siberia and they did just add Yamal. But it is kind of a sparsely populated and inhospitable region, so I’m not sure if there would be much more benefit to breaking it up further. Carving up India and adding to the Americas or filling in the missing parts of China would be more productive.
