But let me stop you right there and ask you, if you think the white race is a real thing. Because if it requires at a minimum to be "largely" isolated from others, but you and I can't collectively identify with certainty where or when that isolation happened - I don't think either of us can definitively even say if "white" is a real race based on those requirements.
Ok! When and where?
I mean at this point this is just hilarious, because you've said white people are a real thing, and they were isolated from other people at some point (15000 BC???) which made the race form but you can't say exactly when or where that happened. So you, supposedly great at "formal logic" have no idea when this thing started existing, its existence by your definition would have been passed down to now from that point through ancestry, and yet you are somehow certain that it exists.
I don't think I could make a good map of where the White race has lived over time even if I watnted to. I think it started somewhere in Europe in like 15,000 BC (very roughly), then spread throughout Europe, then had a colonial period during the last millennia where it colonised all over the world. Certainly I'm very far from an expert on this and it would depend obviously on the exact definition of the White race being used.