The poem by W. B. Yeats noted in Alice's posting above is not entirely original with Yeats. Here is a piece from R. H. Robbins, 'Secular Lyrics', #15, a 14th century fragment from Bodleian MS Rawl. D. 913.]

Ich am of Irlaunde,
ant of the holy londe
of irlande.

Gode sire, pray ich þe,
for of saynte charite,
come ant daunce wyt me
In irlaunde.