Where does “butānietis” come from?

butānietis (Latvian) comes from Latvian -ietis — Added to nouns and adjectives to form masculine (-nieks) or feminine (-niece) nouns referring to people having the properties of the original noun, or living in the place designated by the original noun.

butānietis (Latvian): Bhutanese, a Bhutanese man, a man from Bhutan;...