I used to plan history-inspired campaigns dividing the races into different cultures... But these days my philosophy has changed. I think you can have established historic cultures without forcing a race on them.
For example, I think the California Gold Rush is a fascinating time in history that I would enjoy basing a Weird West D&D campaign on. But rather than saying "Americans are Dwarves, English are Halflings, Chinese are Elves" or whatever (I picked these totally arbitrarily... other than the Halflings

), I think I would let players pick whatever race and culture they want. Why wouldn't there be Dragonborn immigrants coming to California from South America, Russia, etc? And Dragonborn belonging to California native peoples (Ohlone, Miwok, etc)?