“So here we have two worlds of music contained in a single instrument. There’s the “official” world of Western European tonal theory as taught in schools, and there’s the “unofficial” world of the blues, as taught in very few schools, but practiced everywhere in the culture, from the most abstract jazz to top forty radio. Not much music in everyday American life strictly follows the rules of Western tonality. Nursery rhymes do, because they come from the European folk tradition. Hymns, older showtunes, and very conservative pop music mostly do too, for the same reason. But most other current music is informed by the African diaspora.”

Most other current Western music. There is a strong tradition of Indian harmonica music.

https://www.thehindu.com/features/friday-review/hum-along-wi...

Probably elsewhere in Asian music, since it is a cheap, portable and robust musical instrument.

http://frescoharmonica.com/