On November 1, 1956 Andhra State and Telangana region of Hyderabad State are merged to form a united Telugu-speaking state of Andhra Pradesh to form the first linguistic state. Non-Telugu speaking parts of Hyderabad State are merged with Maharashtra and Karnataka. For info wiki Fazal Ali commission, Gentlemen Agreement and etc.,
[edit] SRC (Fazal Ali Commission)

Para 382 of States Reorganization Commission Report (SRC) said "opinion in Andhra is overwhelmingly in favour of the larger unit, public opinion in Telangana has still to crystallize itself. Important leaders of public opinion in Andhra themselves seem to appreciate that the unification of Telangana with Andhra, though desirable, should be based on a voluntary and willing association of the people and that it is primarily for the people of Telangana to take a decision about their future".