Nobiin is one of the about eleven Nubian languages. It has traditionally been grouped with the Dongolawi cluster, mainly based on the geographic proximity of the two (before the construction of the Aswan Dam, varieties of Dongolawi were spoken north and south of the Nobiin area, in Kunuz and Dongola respectively). The uniformity of this 'Nile-Nubian' branch was first called into doubt by Thelwall (1982) who argued, based on lexicostatistical evidence, that Nobiin must have split off from the other Nubian languages earlier than Dongolawi. In Thelwall's classification, Nobiin forms a Northern branch on its own whereas Dongolawi is considered part of Central Nubian, along with Birged (North Darfur) and the Hill Nubian languages (Nuba Mountains, Kordofan).