I think it's safe to say Portugal (trade) and the Zulu (Africa) are involved, and probably Assyria from the looks of it (awesome!), but beyond that, and Poland obviously, who really knows? The Africa scenario makes Congo a possibility, and possibly even Belgium (though I wouldn't count on that one). Probably a native American civ as well, I'd bet on the Sioux (well-known and in past games).
Since we can't really say which ones will be included, the best we can do is rule certain ones out. As a rule I wouldn't expect to see anything that's already covered to a significant degree by another civ. So don't expect Hungary, Finland, Norway, the Maori, Mali, any pre-modern (east)-Indian state... and especially Italy, whose CAPITAL is the capital of another civ, which is obviously unworkable! Sumer and the Hittites are probably out if Assyria is included (Assyria and Babylon cover ancient Mesopotamia pretty well).
Carthage largely covers the Phoenecians, but not geographically - Tyre and Carthage are on different ends of the sea. The Iroquois kind of cover Canada, but only the south-eastern part of it (which is, if you've looked at a map, a rather small portion of a very large country); I wouldn't rule Canada out for that reason, but it's obviously unlikely, I only mention it because [a] the CN Tower wonder in G&K a lot of the obvious major nations have already been used/will be used in this expansion, so what do they lose by throwing a bone to Canadian fans? Finally, [c] the modern-era focus of this expansion indicates it's not outside the realm of possibility that modern nations will be included. (So maybe Brazil? They're on fire these days, and they would fill a notably-empty spot on Earth-maps. Same with Indonesia.)
Also I would rule out any other Eastern European civs (because Poland's got that area covered). If Portugal makes it in too, Europe on Earth maps will be a very crowded place as it is...
„Polak, Węgier, dwa bratanki, i do szabli, i do szklanki.”
Maybe a screenshot hint, though.
