The Sikkim merger occurred after years of political instability and pressures from India. In 1947, India gained independence, and Sikkim remained a protectorate of India. However, in the early 1970s, following an internal political crisis and pressure from the Indian government, Sikkim held a referendum in which the majority of the people voted in favor of merging with India. As a result, Sikkim officially became the 22nd state of India on May 16, 1975.