An unclassified language is a language whose genetic affiliation to other languages has not been established. Languages can be unclassified for a variety of reasons, mostly due to a lack of reliable data but sometimes due to the confounding influence of language contact, if different layers of its vocabulary or morphology point in different directions and it is not clear which represents the ancestral form of the language. Some poorly known extinct languages, such as Gutian and Cacán, are simply unclassifiable, and it is unlikely the situation will ever change. A supposedly unclassified language may turn out not to be a language at all, or even a distinct dialect, but merely a family, tribal or village name, or an alternative name for a people or language that is classified. If a language's genetic relationship has not been established after significant documentation of the language and comparison with other languages and families, as in the case of Basque in Europe, it is considered a language isolate – that is, it is classified as a language family of its own. An 'unclassified' language therefore is one which may still turn out to belong to an established family once better data is available or more thorough comparative research is done. Extinct unclassified languages for which little evidence has been preserved are likely to remain in limbo indefinitely, unless lost documents or a surviving speaking population are discovered. Classification challenges An example of a language that has caused multiple problems for classification is Mimi of Decorse in Chad. This language is only attested in a single word list collected ca. 1900. At first it was thought to be a Maban language, because of similarities to Maba, the first Maban language to be described. However, as other languages of the Maban family were described, it became clear that the similarities were solely with Maba itself, and the relationship was too distant for Mimi to be related specifically to Maba and not equally to the other Maban languages. The obvious similarities are therefore now thought to be due to borrowings from Maba, which is the socially dominant language in the area. When such loans are discounted, there is much less data to classify Mimi with, and what does remain is not particularly similar to any other language or language family. Mimi might therefore be a language isolate, or perhaps a member of some other family related