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Ngmgbang (Riban, Rigmgbang) was formerly listed as a dialect of Bishi, but is clearly a distinct although related language. It is spoken in a few villages in Kaduna State.
References
Piti at Ethnologue (18th ed., 2015) (subscription required)
^ Blench, Roger (2019). An Atlas of Nigerian Languages (4th ed.). Cambridge: Kay Williamson Educational Foundation.