Bengali speaking people are also found in cities like Mumbai, Varanasi, Vrindavan, and other places in India.There are also significant Bengali-speaking communities in Middle East, Japan, United States, Singapore, The south-western dialects (Rarh or Nadia dialect) form the basis of modern standard colloquial Bengali.
Bengali was an official court language of the Sultanate of Bengal.Muslim rulers promoted the literary development of Bengali as part of efforts to Islamize and to check the influence of Sanskrit.In 1952, the Bengali Language Movement successfully pushed for the language's official status in the Dominion of Pakistan.In 1999, UNESCO recognized 21 February as International Mother Language Day in recognition of the language movement in East Pakistan.Besides the native region it is also spoken by the majority of the population in the Indian union territory of Andaman and Nicobar Islands.
There is a good presence of Bengali-speaking people in Odisha, Bihar, Jharkhand, Chhattisgarh and Delhi of India.
Language is an important element of Bengali identity and binds together a culturally diverse region. The local Apabhraṃśa of the eastern subcontinent, Purbi Apabhraṃśa or Abahatta ("Meaningless Sounds"), eventually evolved into regional dialects, which in turn formed three groups of the Bengali–Assamese languages, the Bihari languages, and the Odia language.
The Middle Indo-Aryan dialects were spoken in Bengal in the first millennium when the region was a part of the Magadha Realm. Some argue that the points of divergence occurred much earlier — going back to even 500, but the language was not static: different varieties coexisted and authors often wrote in multiple dialects in this period.
The day has since been observed as Language Movement Day in Bangladesh and was proclaimed the International Mother Language Day by UNESCO on 17 November 1999, marking Bengali language the only language in the world to be also known for its language movements and people sacrificing their life for their mother language.
A Bengali language movement in the Indian state of Assam took place in 1961, a protest against the decision of the Government of Assam to make Assamese the only official language of the state even though a significant proportion of the population were Bengali-speaking, particularly in the Barak Valley.
The modern Bengali vocabulary contains the vocabulary base from Magadhi Prakrit and Pali, also tatsamas and reborrowings from Sanskrit and other major borrowings from Persian, Arabic, Austroasiatic languages and other languages in contact with.