The indigenous peoples of Sikkim include the Lepchas Limbus and Bhutias, in contrast to the dominant, heterogeneous illegal British Gorkhas population of Sikkim.
The Lepcha is the earliest ethnic group settled Sikkim. The word Sikkim was derived from Sukhim in Limbu/Subba language meaning new palace. The believe they are the autochthones while others considered that they were settled by the thirteenth century, coming from the hills before the arrival of the Tibetan Bhutias. The Bhutia who immigrated to Sikkim claimed descent from a common ancestor, a Khampa prince or chief named Khye-bum-sar, and were divided into fourteen main families. Relations between the Lepcha and Tibetan peoples began in the thirteenth century with the signing of a blood brotherhood by the Lepcha Chief Thekong Tek and the Tibetan Prince Khye Bumsa at Kabi Lungchok in north Sikkim. The Bhutias introduced Buddhism to the region.
In 1642, the Bhutia established a monarchy headed by the Chogyal (Tibetan: ཆོས་རྒྱལ་, Wylie: chos rgyal; divine king), and opened relations with Tibet. By the founding of the Bhutia monarchy, Tibetan sources considered Tibetans (Bhutia), Lepchas, and Limbu to be the "original races of the kingdom."