Sikkim lost its protectorate status in 1975 after a tripartite agreement was signed between the Indian Government, the Chogyal (Sikkim’s Monarch) and the political parties representing Sikkim. In the same year, Sikkim became the 22nd state to join the Indian Union.
Sikkim had been made a protectorate by the British in 1861. A protectorate is a state that is controlled by a different sovereign body; however, internal affairs are still managed by local bodies. In the case of Sikkim, the kingdom was ruled by the Chogyal. After independence India took on the same responsibilities that the British had towards the kingdom. Sikkim had autonomy over all domestic matters but defence, communications and external affairs would be managed by the Indian state.
Under the government of Indira Gandhi, Sikkim merged with India after state-sponsored protests broke out on Chogyal Palden Thondup Namgyal’s birthday 4 April, 1975. The violence continued and the king was unable to control the crowds and rioting. Two days later, the tripartite agreement was signed. On 16 May 1975 Sikkim joined the Indian union.