Along with other Eastern Indo-Aryan languages, Bengali evolved circa 1000–1200 CE from eastern Middle Indo-Aryan dialects such as the Magadhi Prakrit and Pali, which developed from a dialect or group of dialects that were close, but not identical to, Vedic and Classical Sanskrit. Literary Bengali saw borrowings from Classical Sanskrit, preserving spelling while adapting pronunciation to that of Bengali, during the period of Middle Bengali and the Bengali Renaissance. The modern literary form of Bengali was developed during the 19th and nearly 20th centuries based on the dialect spoken in the Nadia region, a west-central Bengali dialect. Bengali presents a strong case of diglossia, with the literary and standard form differing greatly from the colloquial speech of the regions that identify with the language.[8] Standard Bengali in West Bengal and Bangladesh are marked by some differences in usage, accent, and phonetics. Today, literary form and dialects of Bengali constitute the primary language spoken in Bangladesh and the second most commonly spoken language in India.

With a rich literary tradition arising from the Bengali Renaissance, Bengali binds together a culturally diverse region and is an important contributor to Bengali nationalism. In former East Bengal (today Bangladesh), the strong linguistic consciousness led to the Bengali Language Movement, during which on 21 February 1952, several people were killed during protests to gain its recognition as a state language of the then Dominion of Pakistan and to maintain its writing in the Bengali script. 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.