Today , Tibetan Buddhism is found in the Tibetan Plateau , Nepal , Bhutan , Mongolia , Kalmykia , Siberia , and the Russian Far East . Today , Tibetan Buddhism is adhered to widely in the Tibetan Plateau , Nepal , Bhutan , Mongolia , Kalmykia ( on the north-west shore of the Caspian ) , Siberia ( central Russia , specifically Buryatia and Chita Oblast ) , and the Russian Far East ( concentrated in Tuva ) .