L1 users: 30,000 (2007 survey), increasing. Includes only the Koch of Garo Hills, Meghalaya, India. No monolinguals. Total users in all countries: 36,000.
Assam state: Goalpara and Nagaon districts; Meghalaya state: West Garo Hills district; Bihar, Tripura, and West Bengal states.
Harigaya, Margan (Dasgaya), Tintekiya, Wanang. Tintekiya in Meghalaya is intelligible with same dialect in Bangladesh; Tintekiya not intelligible with other Koch dialects; Koch-Rabha and Harigaya are mutually intelligible with Wanang; Dasgaya and Harigaya are mutually intelligible; these form a dialect chain (Koch-Rabha-Wanang-Harigaya-Dasgaya-Tintekiya). Lexical similarity: 90% between Tintekiya Koch of India and Bangladesh; Tintekiya: 44%–55% with other Koch dialects; Kock: 31%–39% with Rongdani Rabha [rah], 13%–17% with Garo [grt]. Lexical borrowing is heavier when it comes to high register vocabulary; Koch has borrowed words from Bangla [ben], Assamese [asm] and Hajong [haj].
Vigorous. Non-Koch in Koch villages normally speak Koch. Only 6 of the 8 endogamous groups still speak their mother tongue: Tintekiya, Wanang, Harigaya, Dasgaya, Chapra, and Koch-Rabha. Sankar and Satpariya have no known speakers. All domains. All ages. Positive attitudes. Also use Assamese [asm], Bengali [ben], Boro [brx], English [eng], Garo [grt], Hajong [haj], Hindi [hin], Nepali [npi], Rabha [rah].
Bengali (Bangla) script [Beng].
A Scheduled Tribe in Meghalaya. Koch-Rabha belongs to Koch linguistically and ethnically but claims identity with the Rabha for political reasons. Traditional religion, Christian, Hindu.