The Constituent Assembly adopted the Constitution of India, drafted by a committee headed by Dr. B. R. Ambedkar, on 26 November 1949. India became a sovereign, democratic, republic after its constitution came into effect on 26 January 1950. Dr. Rajendra Prasad became the first President of India.n 1974, India tested its first nuclear weapon in the desert of Rajasthan. Meanwhile, in the Indian protectorate of Sikkim, a referendum was held that resulted in a vote to formally join India and depose the Chogyal. On 26 April 1975, Sikkim formally became India's 22nd state.