That idea seems to be discredited: https://en.wikipedia.org/wiki/Ural%E2%80%93Altaic_languages

The remaining connections of Korean still fascinated me when I first heard about it: https://en.wikipedia.org/wiki/Altaic_languages

> Various versions included the Turkic, Mongolic, Tungusic and sometimes the Korean and Japonic languages.

I was surprised of a kind of "UEH-ll" sound that you can hear in both modern turkish (their goodbye) and Korean language (don't have an example) and wondered if they had some kind of connection. Apparently they do!