Good Morning!
According to the site hymnsandcarolsofchristmas.com, this carol is of Basque origin. The Basques are an indigenous ethnic group that inhabit a region straddling north-central Spain and south-western France. The carol was collected by Charles Bordes and published in the series Archives de la tradition basque, 1895. Sabine Baring-Gould, who also wrote the hymn, Onward Christian Soldiers, translated the Basque carol into English. Sting recorded this version for his album, If On A Winter’s Night in 2009.
Blessings,
Mimi