Infact the only static musical/poetic culture in Europe is probably the Basques, they have their own accordion driven music called "Trikitixa"- check out Kepa Junkera who is a real innovator of the stuff.
I'm by no means an expert of old folk music but there definately seems to be a tradition of modal music in north west Europe that the diatonic accordion or melodeon has latterly found itself at home in, perhaps replacing pipes.
Though it must be said that Cajun is Cajun and has evolved on another continent!
Re: What's the difference between Cajun & Zydeco styles ?
For the uninitiated, Zydeco music is an American roots music that evolved in Louisiana in the 1800s. It combines the music of Louisiana Creole (a blend of French, Spanish, African and Native American cultures) and Cajun music (a blend of French fiddle tunes, Irish fiddle tunes, German button accordion, Latin rhythms and Appalachian styles).