|15 million (2011)|
|Eastern Nagari (Official in Bangladesh, Assam and West Bengal) Devanagari (rare uses)|
"'Kamtapuri"' or Rangpuri or Rajbangshi is a Bengali-Assamese language spoken by the Rajbongshi people in Bangladesh and India, and Rajbanshi and Tajpuria in Nepal. Many are bilingual in either Bengali or Assamese.
Rangpuri goes by numerous names. In Bangladesh, these include Rangpuri, Bahe Bangla, Ancholit Bangla, Kamta, Polia. In India, there is Kamtapuri, Dutta, Rajbangsi, Rajbansi, Rajbanshi, Rajbongshi, Goalparia, surjapuri, Koch Rajbanshi. Another name of the language is Tajpuri. In Assam it is known as Kochrajbongshi. In Bihar it is known as Surjapuri.
The main dialects are Western Rajbanshi, Central Rajbanshi, Eastern Rajbanshi and Hill Rajbanshi (also known as Koch language).
The Central dialect has the majority of speakers and is quite uniform. There are publications in this language. The Western dialect has more diversity. Lexical similarity is 77 to 89% between the three dialects. The version spoken in the hills has some influence of the local tribal languages and differs quite a bit from the other three. Rajbonshi shares 48 to 55% of its vocabulary with Bengali, and 43 to 49% with Maithili and Nepali.
Comparison with other Bengali-Assamese languages
|Muĩ kôrû||Môi kôrû||Ami kôri||Mui xori||I do|
|Muĩ kôrûsû||Môi kôri asû||Ami kôrchi/kôrtechi||Mui xoriar/xorram||I am doing|
|Muĩ kôrsinû||Môi kôrisilû||Ami kôrêchi||Mui xorsilam||I did|
|Muĩ kôrûsinû||Môi kôri asilû||Ami kôrchilam||Mui xorat aslam||I was doing|
|Muĩ kôrim||Môi kôrim||Ami kôrbo||Mui xormu||I will do|
|Muĩ kôrtê thakim||Môi kôri/kôrat thakim||Ami kôrtê thakbo||Mui xorat taxmu||I will be doing|
- Hammarström (2015) Ethnologue 16/17/18th editions: a comprehensive review: online appendices
- Kamta/Rangpuri at Ethnologue (18th ed., 2015)
Rajbanshi at Ethnologue (18th ed., 2015)
Kayort at Ethnologue (18th ed., 2015)
- Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, eds. (2017). "Rangpuri". Glottolog 3.0. Jena, Germany: Max Planck Institute for the Science of Human History.
- Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, eds. (2017). "Rajbanshi". Glottolog 3.0. Jena, Germany: Max Planck Institute for the Science of Human History.
- Toulmin, Mathew W S (2006). Reconstructing linguistic history in a dialect continuum: The Kamta, Rajbanshi, and Northern Deshi Bangla subgroup of Indo-Aryan (Ph.D.). The Australian National University.