Sikkim's people are predominantly of Nepalese extraction; the minority Bhotias (Tibetan in origin) and aboriginal Lepchas are mainly pastoral nomads. Although the Nepalese practice Hinduism, Buddhism was professed by the former chogyal (king under the religious laws) and the official class, and Sikkim is noted for its Buddhist monasteries. Tibeto-Burmese languages and dialects are spoken widely.

In the 16th cent. Tibetans began to settle Sikkim, whose native Lepchas were probably converted to Buddhism by Tibetan lamas. In 1642 a Tibetan king started a hereditary line of Sikkimese rulers that lasted until 1975. Gurkhas from Nepal invaded Sikkim several times in the 18th and 19th cent., but the British, expanding their presence in India, forced the Gurkhas out of Sikkim (1814–16). Later (1835, 1849) the Sikkimese had to cede territory to the British, who assumed a protectorate. China, nominal suzerain of the area, finally recognized the protectorate in 1890, after a British victory over Tibet, but continued to maintain a claim over the area and later did not acknowledge that Sikkim was an Indian state until 2005.

British protection ended when India won independence in 1947, but political and social unrest in newly independent Sikkim led to a treaty (1950) by which the kingdom became an Indian protectorate. India directed defense and foreign relations and communications, while Sikkim retained internal autonomy. India financed construction of strategic roads traversing the mountain passes, thus ending Sikkim's long isolation from the outside world. Sikkim's administration was turned over to India in 1974, and in 1975 India ended Sikkim's last vestiges of independence, deposing the kingdom's chogyal. Sikkim became India's 22d state. It is governed by a chief minister and cabinet responsible to a unicameral legislature and by a governor appointed by the president of India.