Lorient in Brittany hosts an Interceltique festival; it's a cross-cultural festival that celebrates art, food, language, but it's centered around music and features the best bands from Ireland, Scotland, Wales, The Isle of Man, Cornwall, Brittany, Galicia, Cape Breton, PEI, and New Brunswick.
I've gone several times as an accompanist attached to Irish bands, and it's remarkable to me how I can sit in with other musicians from any of those regions and the idioms, base tunes, time signatures, and ornamentation are so similar. I grew up speaking Irish, and while I can understand Scottish Gaelic, I can't follow anything but a word or two of other other Celtic languages. But with music and dance, things seem much much closer. I have to listen and learn much much more to play with other regional folk music, like Eastern European or even French Canadian (which is sort of close to Celtic and shares many tunes), but with the Celtic countries, I've literally sat in on main stages with no rehearsal and we just all know what to do. It does feel like there is quite a deep shared history there.
I've gone several times as an accompanist attached to Irish bands, and it's remarkable to me how I can sit in with other musicians from any of those regions and the idioms, base tunes, time signatures, and ornamentation are so similar. I grew up speaking Irish, and while I can understand Scottish Gaelic, I can't follow anything but a word or two of other other Celtic languages. But with music and dance, things seem much much closer. I have to listen and learn much much more to play with other regional folk music, like Eastern European or even French Canadian (which is sort of close to Celtic and shares many tunes), but with the Celtic countries, I've literally sat in on main stages with no rehearsal and we just all know what to do. It does feel like there is quite a deep shared history there.