When India gained independence in 1947, the British, left the choice of independance or unification up to the local rulers of the princely states. The Muslim ruler of Hyderbad, the last Nizam, wished to remain independent. First he tried to declare Hyderabad as a part of Pakistan but the British government did not allow this. Later in the same year, he announced his intention to become independent.
Qasim Razvi's armed militias known as Razakars had moral support of Pakistan and the Nizam thought that he could rule with the help of this militia. The Razakars troubled the Hindus in every conceivable way.
Some people of the Hyderabad state rebelled against the Nizam. The Communist Party of India succeeded in organizing some peasants. The Telangana peasant armed struggle was successful in driving out local Muslim landlords called Zamindars, and distributing their land to the landless. Nizam sought the help of Razakars, a local Muslim rogue militia, to suppress the rebellion. Qasim Rizvi, also known as Kasin Razvi, the ring-leader of Razakaars, had also stated at one point of time that he "aims to hoist the Islamic flag on Delhi's Red Fort." In 1947-48, Rizvi unleashed his forces in support of the Nizam’s claims to independence and thousands — both Hindus and Muslims opposed to Osman Ali Khan — were killed before the Indian Army swept into the State in September 1948.
The 'Police Action' (officially Operation Polo) by Indian forces neutralized the Razakars, paving the way for absorption of Hyderabad into India.
There was widespread violence against the Muslims as an aftermath of the Police Action and Nehru had a committee investigate the pogrom against Muslims, but the resulting Sundarlal Report was never made public.