did you see the webpage? there are such things as the sparfund effect right? lexicology says a lot.
I mean looking at all the evidence it clearly points out the koreans have far more similarities in dna, and lexicology, and traditional beliefs such as shamanism were are things that tie the altaics together.
prior to han chinese influences koreans, were mainly shamanistic, did not wear silk, weren't buddhist, were warrior like, traditionally nomadic, largely similiar to mongolian or manchurian counterparts.
The Japanese-Korean-Mongolian Connection
From my lexical analysis of the Japanese, Korean, and Mongolian languages, it appears that the Japanese language has a much closer connection to Mongolian.
Of course all three languages have EXACTLY the same grammar (same syntax; AND, all three have the same suffix-like particles), and all three have VERY similar phonological traits, such as rules regarding vowel harmony.
Yet, when I write "much closer", I simply mean that there are more words in Japanese which bear resemblance to Mongolian, but the connection is still a weak one.
The Korean-Japanese ties go way back. It has been told me that the Koreans introduced the Chinese characters to the Japanese. Whether this is true or not, is not known to me, but it seems very plausible, given the geographical situation (i.e., Korean being between China and Japan). The Japanese language, like Korean has "borrowed" a heck of a lot of words from Chinese. But, both the Korean language and Japanese languages have retained many of their "original" lexis as well. It is of this "original" lexis that I write, when I write about the connection to the Mongolian langauge.
However, due to the fact that much of the "original" lexis has fallen out of use and has become lost over the centuries, it is really difficult for linguists to "classify" the two languages.
Because the syntax and phonological features are remarkably similar to Altaic languages, it is logical to include them in the Altaic language group. However, due to lexical differences, it is difficult to place them in any specific language group.
Look at the following diagram to see what I mean:

Source
One can see where I got the above information from, however, my language map is different (and superior, in my opinion, because it shows more clearly how languages "overlap").
Important Points to consider (refer to diagram above):
1. The diagram shows how the Korean language has roots in the Tungusic Language group AND NOT THE MONGOLIAN language group. Note: Manchurian is part of the Tungusic language group, and Korean may have some roots from the Manchu language.
2. The diagram shows how the Korean and Japanese languages have been heavily influenced by the Han-Chinese language.
3. The diagram shows how the Japanese lanugage has some roots in the Mongolian language group. Hence, the lexis of "pure" Japanese is closer to Mongolian than that of the "pure" Korean.
4. The diagram shows how the Korean language has been influenced by the Austronesian language group.
5. It is not known (by me) whether the Japanese language has been influenced by the Austronesian language group or not. Therefore, I have not extended the Japanese language into that "field".
6. The funny thing is, according to genetic maps (on above SOURCE page), the Koreans and Japanese are more closely related to Tibetans than Mongolians. (see diagram below):
also manchuria was home to a lot of nomadic tribes. and all altaic tribes or ethnicities were nomadic at one point.
certainly charts the dna of koreans and the tungustic people are certainly related very much to the korean people.