Magadhi Prakrit
Although Sanskrit was practised by Hindu Brahmins in Bengal since the first millennium BCE, the local Buddhist population were speaking in some varieties of the Prakrita languages. These varieties generally referred to as "eastern Magadhi Prakrit", as coined by linguist Suniti Kumar Chatterji, as the Middle Indo-Aryan dialects were influential in the first millennium when Bengal was a part of the Magadhan realm. The local varieties had no official status during the Gupta Empire, and with Bengal increasingly becoming a hub of Sanskrit literature for Hindu priests, the vernacular of Bengal gained a lot of influence from Sanskrit. Magadhi Prakrit was also spoken in modern-day Bihar and Assam, and this vernacular eventually evolved into Ardha Magadhi. Ardha Magadhi began to give way to what is known as Apabhraṃśa, by the end of the first millennium. The Bengali language evolved as a distinct language over the course of time.