Ethnicity and race are distinct concepts. Come out of your bubble, the world is not US. It is an important distinction to understand what is really going on in the world.

I make very arbitrary example. Lets take Poles and Russians. Both usually pale skinned, slavish people. Still they have such huge cultural and historical differences that they could not by any change form a single political entity.

Still there could be individuals among them that could argue that darker skinned people who are descendants of their nationals are not really Polish, Russian because of their skin color.

These people are racists. The people who argue that Poles are not Russians are not racists. These are just rational persons.