Khitan appears to have been related to the Mongolic languages;Juha Janhunen states, "[T]he conception is gaining support that Khitan was a language in some respects radically different from the historically known Mongolic languages. If this view proves to be correct, Khitan is, indeed, best classified as a Para-Mongolic language."
The Qianlong Emperor of the Qing dynasty erroneously identified the Khitan people and their language with the Solons, leading him to use the Solon language to "correct" Chinese character transcriptions of Khitan names in the History of Liao in his Imperial Liao-Jin-Yuan Three Histories National Language Explanation (欽定遼金元三史國語解) project.
There are several closed systems of Khitan lexical items for which systematic information is available. The following is a list of words in these closed systems that are similar to Mongolic. Mongolian equivalents are given after the English translation:
^Nordhoff, Sebastian; Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, eds. (2013). "Kitan". Glottolog. Leipzig: Max Planck Institute for Evolutionary Anthropology.
^Herbert Franke, John King Fairbank, Denis Crispin Twitchett, Roderick MacFarquhar, Denis Twitchett, Albert Feuerwerker. The Cambridge History of China, Vol. 3: Sui and T'ang China, 589–906. Part 1, p.364
Franks, H. (1976): "Two Chinese-Khitan Macaronic Poems." In: Heissig, W.-Krueger, J. R.-Oinas, F. J.-Schütz, E. (eds): Tradata Altaica. Wiesbaden, Otto Harrassowitz.
Kane, Daniel (1989). The Sino-Jurchen Vocabulary of the Bureau of Interpreters. Uralic and Altaic Series, Vol. 153. Bloomington, Indiana: Indiana University, Research Institute for Inner Asian Studies. ISBN978-0-933070-23-3.