The Kingdom of Sikkim (Classical Tibetan and Sikkimese: འབྲས་ལྗོངས། Drenjong), earlier known as Dremoshong (Classical Tibetan and Sikkimese: འབྲས་མོ་གཤོངས།, official name until 1800s), was a hereditary monarchy from 1642 to 16 May 1975 in the Eastern Himalayas. It was ruled by Chogyals of the Namgyal dynasty.