User blog comment:Equillibrium/The Elder Scrolls Online on PS4: Questions Answered/@comment-70.112.240.21-20140131000405/@comment-13446185-20140201182142

''"The Reach could be mistaken for one of the petty kingdoms of High Rock; it is full of Bretons, Redguards, Cyrodiils, Elves of all stripes, and even a few misplaced khajiit. The northern and western Holds -- Winterhold Hold, Eastmarch, The Rift, and the Pale, known collectively as the Old Holds -- remain more isolated, by geography and choice, and the Nords there still hold true to the old ways. Outsiders are a rarity, usually a once-yearly visit from an itinerant peddler."''

-Pocket Guide to the Empire, First Edition: Skyrim

The Reach is the only Hold at this time to contain multiple races, and during ESO, the Reachmen have complete control of the Reach (and they are quite ethnocentric). I highly doubt that there is a large diversity in Skyrim.