Earlier quoted context omitted.
So it's very reasonable to point out that there's rarely such thing as 'pure ethnicity' and especially the 'lensing' issue of scale is insightful, and of course that some eras there's more evolution than that others ... ... but none of this upsets the fact that ethnicity is the 'primary weight' in the ultimate definition of borders, other than the borders which are artificial (i.e. political) which is why those tend…
You’re begging the question of why ethnicity implies borders. Borders are purely political objects. Without states, there are no borders. Labeling geographic areas as being primarily inhabited by descendants of a certain ethnicity does not at all imply that there is a well-defined point at which one ethnicity becomes another ethnicity in those areas. You can’t just ignore the existence of the nation-state in discussi…
"Without states, there are no borders"
Well, the 'Nation State' is a modern concept, so no.
But if you were to say 'borders imply an administrative region of some kind' - then maybe.
But even without official, stated administrative organization, 'borders' still exist as the demarcation point between groups.
"You can’t just ignore the existence of the nation-state in discussing borders."
I absolutely did not, and I have no idea what you are referring to here.
"your argument here completely falls apart for America. "
No, it doesn't.
Start with the point that most 'states' (or administrative regions) in history, have been ethnocentric. From Egypt through Minoan, Greek, Roman etc..
Some more so than others. The US, no, Sweden, mostly.