The aim of this article is to compare the functions (or meanings) of instrumental case markers in Korean, Mongolian and Manchu. The range of research is not limited to synchronic comparisons, but also include diachronic comparisons. In this article, the functions of the instrumental case marker are divided into 11 categories.
Based on modern and old language, there are more common features between Korean and Mongolian. However there are considerable differences between Korean and Manchu-Jurchen.
Geographically, Manchuria is between the Korean Peninsula and Mongolia. If the borrowing caused by contact between regions created something in common, Korean and Mongolian should be the farthest, and Manchu should have a characteristic in the middle. However, the comparisons are difficult to interpreted as such.
Moreover, the commonality between old Korean and old Mongolian is slightly greater than that of modern languages, which seems to be a meaningful phenomenon. It is worth noting that the functions which have been pointed out as major differences, are almost invisible in old-language data.
Why the functions were more similar in the past, is not easy to point out. Whether the function of the instrumental case marker was due to the natural universality of the world’s languages or traces of the linguistic affinity, will be known only after further research.