People descended from Scythians. Western Europe. Anglo Saxons, Normans, Britons, Scandinavians, etc etc. Why is that impossible to define? White people are a race with subcategories, just as much as blacks or Asians (mongols)

We've seen people who can't define "woman," either. That doesn't mean a definition doesn't exist. It generally means it's so obvious that people haven't put a lot of thought into how to express a definition, or that one is a leftist refusing to define something obvious for political reasons.