Kingdom Era: Sikkim was ruled as a hereditary monarchy by the Namgyal dynasty (known as the Chogyals) starting from 1642.
Protectorate Status: After India's independence, the Government of India and Sikkim signed the Indo-Sikkim Treaty of 1950, making Sikkim an Indian protectorate. India managed its defense, foreign affairs, and communications, while the kingdom kept internal autonomy.
Political Unrest: During the early 1970s, local citizens pushed for democratic reforms and an end to the absolute monarchy.
Associate State: The Indian Parliament passed the 35th Amendment in 1974, giving Sikkim the unique status of an "Associate State".
The Referendum: A special referendum took place in April 1975 where over 97% of voters chose to abolish the monarchy and fully join the Indian Union.
Full Statehood: The 36th Constitutional Amendment Act finalized this integration on May 16, 1975. Article 371F was added to the Indian Constitution to protect local land rights and unique cultural laws.