This article contains Bengali text. Without proper rendering support, you calendar with time slots see question marks, boxes, or other symbols. A revised version of the calendar is the national and official calendar in Bangladesh and an earlier version of the calendar is followed in the Indian states of West Bengal, Tripura and Assam.
The New Year in the Bengali calendar is known as Pohela Boishakh. It is 594 less than the AD or CE year in the Gregorian calendar if it is before Pôhela Bôishakh, or 593 less if after Pôhela Bôishakh. A revised version of the Bengali calendar was officially adopted in Bangladesh in 1987. Among the Bengali community in India, the tradition Bengali Hindu calendar continues to be in use, and it sets the Hindu festivals.
According to Shamsuzzaman Khan, and Nitish Sengupta, the origin of the Bengali calendar is unclear. Some historians attribute the Bengali calendar to the 7th century Hindu king Shashanka. Shiva temples many centuries older than Akbar era, suggesting that a Bengali calendar existed long before Akbar’s time.
Hindus developed a calendar system in ancient times. Jyotisha, one of the six ancient Vedangas, was the Vedic era field of tracking and predicting the movements of astronomical bodies in order to keep time. The ancient Indian culture developed a sophisticated time keeping methodology and calendars for Vedic rituals. The Hindu Vikrami calendar is named after king Vikramaditya and starts in 57 BCE.
In rural Bengali communities of India, 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 Bengali calendar starts from 593 CE suggesting that the starting reference year was adjusted at some point. Various dynasties whose territories extended into Bengal, prior to the 13th-century, used the Vikrami calendar.
For example, Buddhist texts and inscriptions created in the Pala Empire era mention “Vikrama” and the months such as Ashvin, a system found in Sanskrit texts elsewhere in ancient and medieval Indian subcontinent. These calculations about the sun appears in various Sanskrit astronomical texts in Sanskrit, such as the 5th century Aryabhatiya by Aryabhata, the 6th century Romaka by Latadeva and Panca Siddhantika by Varahamihira, the 7th century Khandakhadyaka by Brahmagupta and the 8th century Sisyadhivrddida by Lalla. These texts present Surya and various planets and estimate the characteristics of the respective planetary motion. Other texts such as Surya Siddhanta dated to have been complete sometime between the 5th century and 10th century.
The current Bengali calendar in use by Bengali people in the Indian states such as West Bengal, Tripura, Assam and Jharkhand 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. Yet another theory states that the Sasanka calendar was adopted by Alauddin Husain Shah when he witnessed the difficulty with collecting land revenue by the Hijra calendar.
During the Mughal rule, land taxes were collected from Bengali people according to the Islamic Hijri calendar. This calendar was a lunar calendar, and its new year did not coincide with the solar agricultural cycles.
According to some sources, the current Bengali calendar owes its origin in Bengal to the rule of Mughal Emperor Akbar who adopted it to time the tax year to the harvest. The Bangla year was therewith called Bangabda. According to some historians, this started the Bengali calendar. According to Shamsuzzaman Khan, it could be Nawab Murshid Quli Khan, a Mughal governor, who first used the tradition of Punyaho as “a day for ceremonial land tax collection”, and used Akbar’s fiscal policy to start the Bangla calendar.