Short answers, pulled from the story.
The Indo-Aryans arrived in Bengal during the 3rd century BCE and began a process of Sanskritisation that shaped the language for millennia. Early varieties of Prakrit spoken in the region were called eastern Magadhi Prakrit by linguist Suniti Kumar Chatterji.
A Sanskrit-Chinese dictionary compiled by Chinese poet Li-Yen in 782 AD contains 51 Bengali words, proving Old Bengali existed at least by the 8th century. The ancestor of modern Bengali was the language of the Pala Empire and later the Sena dynasty.
Over 242 million native speakers use Bengali today with another 43 million speaking it as a second language as of 2025. It is the sixth most spoken native language globally and seventh overall by total speakers.
On the 21st of February 1952 five students and political activists were killed during protests near the University of Dhaka campus while resisting the imposition of Urdu. These individuals became the first martyrs to die for their right to speak their mother tongue.
The West-Central dialects known as Rarhi or Nadia dialect form the basis for modern standard colloquial Bengali. Standard Colloquial Bengali developed from the Shantipur and Shilaidaha regions of Nadia and Kushtia Districts respectively.