Pseudotranslation

In literature, a pseudotranslation is a text written as if it had been translated from a foreign language, even though no foreign language original exists. 
History.
The concept of a pseudotranslation was initially proposed by Israeli scholar Gideon Toury in "Descriptive Translation Studies–and Beyond" (1995). The technique allows authors to provide more insight into the culture of the work's setting by presupposing that the reader is unfamiliar with the work's cultural setting, opening the work to a wider world audience.
Writing a pseudotranslation involves using features that usually indicate to a reader that the text is a translation. As some translators have argued, pseudotranslations can be a way of publishing literature that is stylistically different or critical." Scholars such as Gideon Toury also note that readers are more likely to accept texts that differ from the norm if they are culturally distant.
Many works of science fiction and fantasy can be regarded as pseudotranslations from nonexistent languages. J. R. R. Tolkien's "The Lord of the Rings" explicitly claims to have been translated from the ancient languages of Middle-earth, while Gene Wolfe, in the afterword to its first volume, claims that "The Book of the New Sun" series is translated "from a language that has yet to achieve existence".