Inherited from Old Bengali মই (maï), মঞি (mañi /maĩ/), from Magadhi Prakrit 𑀫𑀏 (mae), 𑀫𑀏𑀁 (maeṃ), 𑀫𑀇 (maï), 𑀫𑀇𑀁 (maïṃ), from Sanskrit মযা (máyā), from Proto-Indo-Aryan *máyaH, from Proto-Indo-Iranian *máyaH, the instrumental singular of *aȷ́ʰám (“I”), from Proto-Indo-European *éǵh₂om. Nasal variants arose in Prakrit due to conflation with the general instrumental singular suffix -𑀏𑀁 (-eṃ), from Sanskrit -एन (-ena). Cognate with Sylheti ꠝꠥꠁ (mui), Rohingya mui, Kamta মুই (mui), মইঁ (moĩ), Assamese মই (moi), মইঁ (moĩ), Odia ମୁଁ (mũ), Maithili में (mē̃), Bhojpuri में (mē̃), Old Awadhi मैं (ma͠i), Hindustani میں / मैं (ma͠i), Nepali म (ma), मैं (ma͠i), Kumaoni मैं (ma͠i), Dogri मैं (ma͠i), Punjabi ਮੈਂ (maĩ), Sindhi مَان (mā̃), Ahirani मी (mī), Marathi मी (mī), Phalura ma.
During the time of late Middle Indo-Aryan, the instrumental form of the 1st person singular pronoun became a substitute for the nominative form in most lects. In Old Bengali, মই (maï) ultimately replaced the original nominative form হাঁউ (hā̃u).