it's strange to see that, Cornwall means horn of the foreigners or Britons and that the Britons were considered as foreigners on their ancestral lands 🤷

The names "Wales" and "Welsh" are modern descendants of the Anglo-Saxon word wealh, a descendant of the Proto-Germanic word walhaz, which was derived from the name of the Gaulish people known to the Romans as Volcae and which came to refer indiscriminately to inhabitants of the Roman Empire. The Old English-speaking Anglo-Saxons came to use the term to refer to the Britons in particular. As the Britons' territories shrank, the term came ultimately to be applied to a smaller group of people, and the plural form of Wealh, Wēalas, evolved into the name for the territory that best maintained cultural continuity with pre-Anglo-Saxon Britain: Wales.