The myth of homogeneity

Is there any nation on earth that consists of a single ethnic group? The question is kind of nonsensical, as the ethnic groups you see depends on the question you asked. For instance, when your attention is on the color line in American history, white Americans are a monolith, and so are black people. On many other measures, the differences between say, Irish-Americans and WASPS are important, and native-born African-Americans have to be distinguished from black immigrants.

Still, you can control for the observer effect. Agree on a single definition of ethnicity, stipulate the shared purpose of the inquiry, then look around at the world's nations. Using your single standard, won't you find that some countries are mono-ethnic?

I doubt it. Here's a news story about yet another supposedly one-ethnicity nation that isn't.