Sylheti is the language of Sylhet, the North Eastern province of Bangladesh and a few southern districts of Assam. It is also spoken by a significant population in the other north-eastern states of India. It is similar enough to Bengali for some to consider it a dialect, but is probably better seen as a separate language. Indeed it was formerly written in its own script, Sylheti Nagari, similar in style to Devanagari but significantly simpler. Now it is almost invariably written in Bengali script.
The difference between Sylhet is a tendency to slur aspirated sounds and a vocabulary that is far more given to Arabic and Persian words than standard Bengali found in West Bengal. Sylhet is spoken by about 10% of Bangladeshis, but has affected the course of standard Bangla in the rest of the state.
Sylheti (native name সিলটী Silôţi; Bengali name সিলেটী Sileţi) is the language of Sylhet proper, the North Eastern region of Bangladesh and southern districts of Assam around Silchar.
Sylheti is distinguished by a wide range of fricative sounds (which correspond to aspirated stops in closely-related languages such as Bangla), the lack of breathy voiced stops seen in many other Indic languages, word-final stress, and a relatively large set of loanwords from Arabic, Hindi and Persian.
Sylheti is spoken by about 10 percent of Bangladeshis, but has affected the course of standard Bengali in the rest of the state.
Sylheti is an Eastern Indic language closely related to Bengali (Bangla), Chittagonian, and Assamese (Ôxômiya).
Sylheti is also the dominant dialect of Bengali among the inhabitants of the Barak Valley in India, centered around Cachar district in Assam.
This is illustrated in the court action taken against the makers of the Hason Raja movie, he being a Sylhoti cultural icon, as the film depicted him as a lecherous fellow who forsakes his family and uses obscene language.