But remember – during interwar period, Poland still were multinational – we had here Belarusians, western Ukrainians, Lithuanians, many Jews and Germans. Today's homogeneity is effect of actions after war under USSR command and commie governments (but still final voice had here "uncle Joe"), and postwar division of Europe.
Yes, Operation Vistula was polish action, but remember, we was then under communist rule, and many of polish families suffered after resettlement their relatives and friends from childhood to another country.
I think that Davies could have right with our current "unnatural"(homogenous) state, because even after 123 years of captivity, we was still multi, and our present state was impose by force
PS. If there are some mistakes, please correct it. I'm so tired and I don't think now, so it's time to sleep!