Since the 17th century, Bhutan's official name has been ''Druk yul'' (literally, "country of the Drukpa Lineage" or "the Land of the Thunder Dragon," a reference to the country's dominant Buddhist sect); "Bhutan" appears only in English-language official correspondence. The terms for the Kings of Bhutan, ''Druk Gyalpo'' ("Dragon King"), and the Bhutanese endonym ''Drukpa'', "Dragon people," are similarly derived.