section_path: Traditional and revised versions
section_name: Traditional and revised versions
paragraph_text: Traditional and revised versions
  
  The current Bengali calendar in the Indian states is based on the Sanskrit text Surya Siddhanta. It retains the historic Sanskrit names of the months, with the first month as Baishakh. Their calendar remains tied to the Hindu calendar system and is used to set the various Bengali Hindu festivals.
  
  In Bangladesh, however, the old Bengali calendar was modified in 1966 by a committee headed by Muhammad Shahidullah, making the first five months 31 days long, the rest 30 days each, with the month of Falgun adjusted to 31 days in every leap year. This was officially adopted by Bangladesh in 1987.