The process Jim Carroll describes also applied in Turkey (possibly still does in places) - there are lots of topical songs of 20th century origin with no known composer.

Oddly, songs of the same era in the same musical idiom but with religious/mystical texts (something you don't get in Ireland, as far as I know) usually do have known composers. They tend to come out of the Alevi/Bektashi tradition, where bards belong to documented lineages.