They also usually have one place of origin, or if there are multiple, it's just vaguely in a direction (lots of planets have a north), or an off-world colony, so the whole species is named for the planet they came from.

Martians are from Mars, Vulcans are from Vulcan, Humans are from Hume, etc. You don't tend to have them mention any more specific regions than that. Where on Earth do Earthlings come from? Why, the Earthling city, of course.