Folk is also an art form that is native to a place/traditional, in other words belonging to the local people (folk)
Folk dance, folk stories, folk songs.
"The terms folk music, folk song, and folk dance are comparatively recent expressions. They are extensions of the term folk lore, which was coined in 1846 by the English antiquarian William Thoms to describe "the traditions, customs, and superstitions of the uncultured classes."