Chittagonian

Closely related but linguistically distinct. Most linguists describe Chittagonian and Standard Bengali as separate Eastern Indo-Aryan languages with limited mutual intelligibility — speakers of one need real effort to follow the other. The Bangladeshi state classifies Chittagonian under Bengali for administrative purposes, but on linguistic grounds the two are far enough apart to be considered separate languages.

Across the Chittagong Division of southeastern Bangladesh — the cities and rural districts of Chittagong, Cox's Bazar, Bandarban, and surrounding areas. Chittagonian is also spoken by communities in adjacent Myanmar (the Rohingya share the same broader Eastern Indo-Aryan group, with Rohingya often classified as a separate but closely related variety), and by diaspora populations in the Gulf and the United Kingdom.

No. Bangladesh recognizes Bengali as the official language and treats Chittagonian as a dialect under that umbrella. Chittagonian is widely used at home and in informal contexts but absent from formal education and government administration, where Standard Bengali is used.

The port city of Chittagong has been a major trading entrepôt for centuries — Arab, Persian, Burmese, Portuguese, Dutch, and British traders all passed through and settled. Each left lexical layers in the local language. Chittagonian carries Arabic and Persian vocabulary heavier than Standard Bengali, plus Portuguese loans tied to the early colonial period and English loans from the British era and onward.

Yes — Rohingya, spoken by the Rohingya people of Rakhine State in Myanmar, is a closely related Eastern Indo-Aryan language. Linguists generally treat Rohingya and Chittagonian as separate but mutually intelligible languages of the same broader group. Both differ noticeably from Standard Bengali.