This is what we found on Wikipedia regarding the Onóir:

Irish traditional music (also known as Irish trad, Irish folk music, and other variants) is a genre of folk music that developed in Ireland.

In A History of Irish Music (1905), W. H. Grattan Flood wrote that, in Gaelic Ireland, there were at least ten instruments in general use. These were the cruit (a small rubbed strings harp) and cláirseach (a bigger harp with typically 30 strings), the tiompán (a small string instrument played with a bow or plectrum), the feadán (a fife), the buinne (an oboe or flute), the guthbuinne (a bassoon-type horn), the beannbhuabhal and corn (hornpipes), the cuislenna (bagpipes – see Great Irish warpipes), the stoc and storgán (clarions or trumpets), and the cnámha (bones). There is also evidence of the fiddle being used in the 8th century.

There are several collections of Irish folk music from the 18th century, but it was not until the 19th century that ballad printers became established in Dublin. Important collectors include Colm Ó Lochlainn, George Petrie, Edward Bunting, Francis O'Neill, James Goodman and many others. Though solo performance is preferred in the folk tradition, bands or at least small ensembles have probably been a part of Irish music since at least the mid-19th century, although this is a point of much contention among ethnomusicologists.

Irish traditional music has endured more strongly against the forces of cinema, radio and the mass media than the indigenous folk music of most countries in the west of Europe. From the end of the Second World War until the late fifties folk music was held in low regard. Comhaltas Ceoltóirí Éireann (an Irish traditional music association) and the popularity of the Fleadh Cheoil (music festival) helped lead the revival of the music. Following the success of the Clancy Brothers and Tommy Makem in the US in 1959, Irish folk music became fashionable again. The lush sentimental style of singers such as Delia Murphy was replaced by guitar-driven male groups such as the Dubliners. Irish showbands presented a mixture of pop music and folk dance tunes, though these died out during the seventies. The international success of the Chieftains and subsequent musicians and groups has made Irish folk music a global brand.

Historically much old-time music of the US grew out of the music of Ireland, England and Scotland, as a result of cultural diffusion. By the 1970s Irish traditional music was again influencing music in the US and further afield in Australia and Europe. It has occasionally been fused with rock and roll, punk rock and other genres.