Origins The
Saka Era was the widely used in
Bengal, prior to the arrival of Muslim rule in the region, according to various epigraphical evidence. The
Bikrami calendar was in use by the Bengali people of the region. This calendar was named after king
Vikramaditya with a zero date of 57 BCE. In rural Bengali communities, the Bengali calendar is credited to "Bikromaditto", like many other parts of India and
Nepal. However, unlike these regions where it starts in 57 BCE, the modern Bangladeshi and Bengali calendar starts from 593 CE suggesting that the starting reference year was adjusted at some point.
Akbar's influence Crop cycle's depended on solar calendars. The Islamic
lunar calendar of the Mughal government, before Akbar's era caused problems in tax collection since the lunar year was shorter than the solar year by about eleven days per year. Akbar commissioned his astronomer
Fathullah Shirazi to develop a new syncretic calendar to allow land tax and crop tax collection according to the harvest cycles. In 1584, Emperor Akbar commissioned a new calendar as part of tax collection reforms. It used 1556 as the zero year, the year of Akbar's ascension to the throne. However, Akbar's ideas were almost entirely abandoned after his death, and only traces of the
Tarikh-e-Ilahi calendar survive in the modern Bengali calendar, according to
Amartya Sen.
Shamsuzzaman Khan believed that Nawab
Murshid Quli Khan was responsible for widely implementing the tax collection according to the Bengali calendar throughout Bengal. Khan promoted celebrations of the Punyaha, a ceremonial collection of land taxes. The calendar year became known as the
Bangla san in
Arabic and
Bangla sal in
Persian; both terms mean the Bangla Year.
Modern revisions and adoption In 1966, a committee headed by
Muhammad Shahidullah was appointed in
East Pakistan to reform the traditional Bengali calendar and making it independent of
Hindu astrological influences. It proposed the first five months 31 days long, rest 30 days each, with the month of Falgun adjusted to 31 days in every leap year. In 2018, the Bangladesh government planned to modify the Bangladeshi calendar again. The changes were done to match national days with West. As a result of the modification, Kartik started on Thursday (17 October 2019) and the dry season was delayed by a day as the revised calendar went into effect from Wednesday (16 October 2019). ==Months and seasons==