>>212640904 (OP)There's probably a mistake in your interpretation because everything in Europe that was once "foreign" was etymologically related to "the Gauls" or "the Walloons" or "the Welsh", etc.
Proto-germanic root "Walha*z". That became "Gaul" for the Romans by consonant shift, remained a form of "Walh" (Walloon, Welsh, etc.). Here in Alsace, we call the Alsatians who don't speak Alsatian (related to their territory in the Vosges mountains) "Welches".