Tima
According to the standard classification of African languages by Greenberg (1963), there are four language phyla: Niger-Kordofanian (nowadays referred to as Niger-Congo), Nilo-Saharan, Afroasiatic, and Khoisan. According to the same classification, Tima is part of the Katla cluster within the Kordofanian branch of Niger-Congo, which further includes Katla proper as well as Julud. This is also the position taken by Schadeberg (1981:118, 127), who treats the Katla-group as one of the four subgroups of Kordofanian:

Preliminary data collected by the research team for the documentation of the Tima language has shown, however, that its genetic affiliation needs to be reconsidered. Grammatical evidence strongly suggests that Tima (or more properly, the Katla cluster) is not part of Kordofanian, but instead is more closely related to Niger-Congo subgroups like Benue-Congo and Kwa. With the collection of additional grammatical as well as lexical data, the research team hopes to be able to further classify the genetic status of the Tima language and its closest relatives, Katla and Julud.
The language of the Tima people – which they themselves refer to as Dumurik – is spoken in the Nuba Mountains of north-central Sudan, a residual area with over forty different languages many belonging to different language families. Several factors contribute to the fact that the Tima language and other languages in the Nuba Mountain area are endangered.
Most Tima are multilingual. For example, one Tima informant not only spoke Tima as well as the closely related Katla language, but also neighbouring languages such as Tulishi (a member of the Kadu(gli) group; genetic affiliations not clear), Nyimang (Nilo-Saharan), some Temein (Nilo-Saharan), as well as Arabic. As a result of the civil war in Sudan over the past decades, this informant also spent time in Congo (Zaire), Uganda and Kenya, and consequently learned Lingala, Swahili and English. Multilingualism as such, however, is not the main reason why Tima is an endangered language, as the domains in which such languages are used do not necessarily overlap. However, Arabic, which has become the dominant lingua franca also in the Nuba Mountains, is encroaching upon Tima and other languages in various domains of social interaction between people. Above all, this is due to the fact that today Arabic is the only language playing a role in the educational as well as the administrative system of the country (cf. Mugaddam 2006, and Mugaddam and Dimmendaal, 2005).
Due to the political insecurity (more specifically the civil war) in Sudan over the past decades, many groups from the Nuba Mountains have moved to major urban areas such as Khartoum. Today, there are probably over 1000 Tima people in the larger Khartoum area. Members from this community feel that their language is disappearing rapidly in particular in the Khartoum area, because their children are growing up with Arabic, and no longer learn the language of their parents.
References
Greenberg, J.H. 1963 and 1966. [The] Languages of Africa. Bloomington and Den Haag, Mouton.
Mugaddam, Abdel Rahim. 2006. Language maintenance and shift in Sudan: The case of ethnic migrant groups in Khartoum. The International Journal of the Sociology of Language 181, 123-136.
Mugaddam, Abdel Rahim and Gerrit J. Dimmendaal. 2005. Sudan: Linguistic situation. In Keith Brown (ed.), International Encyclopedia of Language and Linguistics, Vol. 12, pp. 265-270. Oxford: Elsevier.
Schadeberg, Thilo C. Das Kordofanische. In Bernd Heine, Thilo C. Schadeberg and Ekkehard Wolff (eds), Die Sprachen Afrikas, pp. 117-128. Hamburg, Helmut Buske.