I like the Idea of Orcs as Mongolians (especially since they remind me visually of mongols in skyrim)
Me personally
Kahjiit: Mesopotamian, so like Iraq. I think because of their names the "warm sands" quote and very Persian accents (pun not entirely intended) and the gypsy caravans remind me of the Kurdish.
Redgaurd: would be similar to kahjiit but I'd say more like Egypt, scimitars and the headdresses all still apply.
Orcs: like I said Mongolian, they're nomads with a very large focus on tribal hierarchy.
Breton: Celts for sure, they don't seem french to me but for seaside france maybe, My main thought is they are from High Rock which makes me think they are highlanders, that and magic, because I know for sure Ireland has a very large history of fairy tale and such things. so surrounding areas around Britain and some parts of England.
Imperial: well Rome was one of the first imperialist societies right that, the clothing, and the "legates" and very olden sounding names indicates rome.
Nords: vikings, I shouldn't need explain, even Draugr is a Swedish word.
Argonians: I think of rainforest and murky places, I would think southern america like brazil maybe aztecs but I can't even say for sure, could be southeast asian too i suppose.
Elves: I think it would be a safe bet to say the elven races would be very close together which makes it hard to pin down for me. the High elves remind me of British very uppity posh British, dark elves maybe Russia for lack of a better place and wood elves maybe the keibler factory in london.