Stupid thinking there. With your reasoning we shouldn't have Iroqois and Aztecs since we have United States.
My short list is :
1) Byzantium
2) Mongols
3) Spain
4) Vikings
Eh, the Americas are big enough to accomodate two civs, and you could argue that the American state under Washington was mostly the eastern side of the States, so there's more than enough room the Iroquois in middle America and Canada.
The HRE, OTOH, is basically mostly Germany. Same with the Byzantines and Ottomans. Really though the main reason is I want to be able to play Earth with as many civs as possible in their correct spots.
Still, re: Byzantium, it was certainly significant, but with Greece, Rome, & the Ottomans already in the game I feel it's a bit redundant.
And 'stupid thinking'? Apologies for having an opinion.