ThaiNotes

No need. I already have a Masters degree in linguistics. However, I have a question for you: why do you assume that the language group originated in Bengal, when its members are used in Bihar, Nepal, Assam, Arunchal Pradesh, Nagaland, Bangladesh as well as Bengal and elsewhere? And wherever the language originated, it's perfectly possible for one language to displace others. For example, the peoples of South America didn't originally speak Spanish or Portuguese. The fact that the Rohingya speak a language related to Bengali says nothing about where they're from.

There is a large group of languages which are closely related, including Assamese, Bengali, Bishnupriya, Manipuri, Chakma, Chittagonian, Hajong, Rangpuri, Kamtapuri, Rajbongshi, Noakhalian, Rohingya, Surjapuri, Sylheti, Tanchangya - all spoken in that part of the world. To assert that the Rohingya are Bengali just because they speak a language in the same family is ridiculous. It's as ridiculous as suggesting that Spaniards are really Italian because their languages are similar, or that the English are really German because their language evolved from North Sea Germanic (Ingvaeonic).

That's Tatmadaw propaganda and false. They originate from the Arakan region in what is now part of Burma, but historically was independent. See, for example, https://www.sociostudies.org/journal/articles/2759620/