Yeah, it's a term from an outdated racial theory that got into mainstream language. Still keeps weirding me out every time I see it. In Russia where I grew up, actual people from Caucasus region are still often treated and portrayed in media as "black" for being generally slightly darker than slavs. It's disgusting. But, the populations in Caucasus region are actually very diverse. Like, for example, just talking about the skin color, the Azerbaijanis are generally fairly tan, but then quite a few of them are whiter than snow, and that's the diversity within just one ethnic group of which there are few dozens. So I find it just as weird to call white people Caucasian (and people of Caucasus just "white") as it'd be calling them Romanis or Tuaregs (or Jews) for how meaningless that'd be.