遼史
As part of the promotion of Kaozheng studies in the philological field, Qianlong decided that the Chinese character transcriptions of names and words of the Khitan language in the History of Liao, the Jurchen language in the History of Jin, and the Mongolian language in the History of Yuan were not phonetically accurate and true to the original pronunciation. The histories were in fact hastily compiled and suffered from inaccurate and inconsistent phonetic transcriptions of the same names. He ordered the "Imperial Liao Jin Yuan Three Histories National Language Explanation" ( "Qīndìng Liáo Jīn Yuán sān shǐ guóyǔjiě") project to "correct" the Chinese character transcriptions by referring to the contemporaneous descendants of those languages. Qianlong identified the Solon language with the Khitan, the Manchu language with the Jurchen, and the Mongolian language with the Mongolian. Solon, Mongolian, and Manchu speakers were consulted with on the "correct" pronunciations of the names and words and their Chinese transcriptions were accordingly changed. However the Khitan language has now been found by modern linguists to be a Mongolic language and is unrelated to the Solon language. The project was part of the Siku Quanshu. Qianlong also promulgated a theory that the Daur people were descended from a Khitan clan, changing the Khitan clan name "Dàhè", found in the History of Liao, to "Dáhū'ěr". The Chinese transcription of the Manchu clan name Niohuru ("Niǔhùlù") was edited and inserted in place of the Jurchen clan name ("Nǚxīliè").