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 and Daur equivalents are given after the English translation:
^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
Franke, H. (1976). "Two Chinese–Khitan Macaronic Poems". In Heissig, W.; Krueger, J. R.; Oinas, F. J.; Schütz, E. (eds.). Tractata Altaica: Denis Sinor, Sexagenario Optime de Rebus Altaicis Merito Dedicata. Wiesbaden: Otto Harrassowitz. pp. 175–180. ISBN3-447-01798-8.
Kane, Daniel (1989). The Sino-Jurchen Vocabulary of the Bureau of Interpreters. Bloomington, Indiana: Indiana University, Research Institute for Inner Asian Studies. ISBN0-933070-23-3.
Qinge'ertai (Chinggeltei); Yu, Baolin; Chen, Naixiong; Liu, Fengzhu; Xin, Fuli (1985). Qìdān xiǎozì yánjiū [A Study of the Khitan Small Script] (in Chinese). Beijing: Zhongguo shehui kexue chubanshe. OCLC16717597.