Rajbanshi

Koch–Rajbongshi community (also known as Kochrajbongshi and Koch Bihari) is an indigenous community of Koch Bihar origin found in parts of present-day Nepal; the Indian states of Assam, West Bengal, and Meghalaya; and Kishanganj in the state of Bihar and certain parts of Bhutan.

It is commonly believed that the Koch (Rajbansi) population forms a major detribalized group. According to Gait (1905) “In Assam proper, it (the word Koch) has become the name of a Hindu caste, into which are received the converts to Hinduism from the ranks of the Kachari, Lalung, Mikir and other tribes”. However, it is not known from which time the process of conversion started. It is viewed that major part of conversion took place following the preaching of Vaishnavite cult by Srimanta Sankardeva, a socio-cultural reformer and a religious preacher of Assam during the 15th century A.D.

According to a study based on blood sample collection from Koch people from Goalpara (Borigaon area) district of Assam in 1978-1979, Koch of Goalpara disagree with the tribal populations (like the Garo, Kachari and Rabha who form the parental stock) in most of the characters. It has been observed that the Rajbansi (Koch) living in the tribal area were maintaining a high frequency of HbE gene while Rajbansis living in the area of Hindu castes showed "dilution" of the HbE frequency and thereby showed similarity with the Assamese caste groups in this regard. Along all the Bodo speaking tribes, namely the Garo, Rabha, Kachari and Lalung, HbE gene occurs in very high percentage. “Therefore, one may perhaps infer that the Rajbansis of the tribal areas are descendants of the recent converts and as such are still preserving HbE gene in a high frequency,” the study says.

Some speak the Koch language, which is a Sino-Tibetan language closely related to the Bodo language spoken by the Bodo people.

Some speak the Rajbangshi language, which is an Indic language spoken by five million in India, and more than 130,000 by Nepali Rajbanshi and also Tajpuria. Many are bilingual in either Bengali or Nepali.

...
Wikipedia