Koreans and Mongols are related peoples; when the Mongols conquered Korea in the time of Kublai Khan, they left some genetic residue, but not noticeably so. I have heard that modern day Mongolians like Koreans and hate and fear the Chinese.
Well, if Koreans and Mongols are related, wouldn't Korean be considered a ALtaic language? I believe that it's usually considered a language isolate.