The people of that place decide collectively, in a highly unofficial manner. Often it’s just a natural extension of the word that follows grammatically.
When the people in question speak a different first language than the people using the name, it’s different. If the namers speak English, then the name was almost always chosen historically by British conquerers. And frequently, the name given for the people is the same as the name given for their language, e.g. “French,” “Spanish,” “Italian,” etc.
Latest Answers