Crow sister said ( how do you italicise, BTW)
'For the English speaking world, it makes sense to define 'indigenous folk musical traditions', as being distinct from 'non-indigenous traditional musics'.'

Does it. There has always been fusion...sea shanties are a complete mix, with African, West Indian, European etc influences.

   Elsewhere in America different mucics blended in Texas, Louisisna, the Appalachians etc.
    categories are for libraries, not the real world.