But the idea that really caught my interest here is wondering if the type of musical collusions/collisions that made Appalachian music, Cajun music, and the blues are still going on. Or has the prevalence of rock music and the shrinking world made that a thing of the past? Does anyone know of any blending of different types of traditional music to make a new idiom in the last hundred years or so?

Jazz (Black song traditions mixed up with white dance and military music)

French cafe music (northern French bagpipe-based dance music mixed up with jazz harmonies when transferred to the accordion)

Scottish dance music of the same period (similar process starting with the fiddle repertoire, the standard lineup being originally derived from American dancebands of the early 20th century)

Rembetika (Turkish fasil music increasingly mixed up with all kinds of other stuff)

Arabesk (Turkish fasil music with Kurdish folk tunes and Arabic backings)

Tango (Cuban dance rhythms and Argentine song lyrics on German instruments with harmonies from jazz)

Klezmer (Romanian, Ukrainian, Gypsy and Jewish music all mixed up)

The Hungarian "new song" (started in the 19th cetury but really got under way after WW1)

Samba (African dance adapted to urban Brazil around WW1)