One idea would be to search for the traditional instruments of a country, and then look for performances of music using those instruments.
For example, if we search for traditional Korean instruments, a prominent one you'll learn about is the gayageum.
If you then do a web search for traditional gayageum videos, the first hit on google is currently https://www.youtube.com/watch?v=OfTxj8IYMpY, which sounds like a traditional piece to me.
Another way would be to translate the phrase 'traditional music' (or 'folk music', etc.) into the language of the country you're interested in. Sticking with Korea, google translate tells us this is 전통 음악. Again, the first 'hit' for searching google videos for 전통 음악 is https://www.youtube.com/watch?v=NER5qPiFG-s, which is probably within the scope of what you'd be looking for.
You might have trouble searching for traditional music by artist - often the pieces in question will have no known composer. However, if you search for traditional songs or traditional dances of a nation, you should be able to turn up some representative folk music.