The Ijoid, or perhaps just Ijaw, languages form a divergent branch of the Niger–Congo family and are noted for their subject–object–verb basic word order, which is otherwise an unusual feature in Niger–Congo, shared only by such distant branches as Mande and Dogon. Like Mande and Dogon, Ijoid lacks even traces of the noun class system considered characteristic of Niger–Congo, and so may have split early from that family. Linguist Gerrit Dimmendaal doubts its inclusion in Niger–Congo altogether and considers the Ijaw/Ijoid languages to be an independent family. 
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- Hammarström, Harald; Forkel, Robert; Haspelmath, Martin; Bank, Sebastian, eds. (2016). "Ijoid". Glottolog 2.7. Jena: Max Planck Institute for the Science of Human History.
- Roger Blench, Niger-Congo: an alternative view
- Dimmendaal, Gerrit Jan (2011-01-01). Historical Linguistics and the Comparative Study of African Languages. John Benjamins Publishing. ISBN 9027211787.
- Babaev, Kirill. "Joseph Greenberg and the Current State of Niger-Congo".