Sikkim became the 22nd State of India under the Constitution 36th Amendment Act 1975
Background
The Sikkim Legislative Assembly records that Sikkim became the 22nd State of India Vide Constitution(36th Amendment) Act 1975. Sikkim was a tiny Himalayan kingdom once ruled by the hereditary monarchy for about 3 centuries from 17 century A.D. In 1950 the kingdom became a protectorate of the Government of India vested with autonomy in its internal affairs, with its defence, communications and external relation under the responsibility of the protector. The kingdom finally opted to become full fledged State of the Indian Union with effect from 26 April, 1975 vide the Constitution 36th Amendment Act 1975. Special provision was laid for the State under article 371(F) of the Constitution of India. The Act provides that the Legislative Assembly of Sikkim shall consist of not less than thirty two members. The Assembly of Sikkim formed as a result of the elections held in Sikkim in April, 1974 with 32 members elected in the said elections was deemed to be the legislative Assembly of the State duly constituted under the Constitution. The State has a geographical area of 7096 kms.
In plain words
Protectorate Protectorate of the Government of India — A state whose defence, communications and external relations are the responsibility of a protecting power.