This carol is old. Like, really old. Like, medieval old.It's so old, in fact, that no one is quite sure the exact year, decade, or even century in which it was first performed.
The oldest known sheet music for "Greensleeves" (as the song was known in the Middle Ages) was registered in London in 1580, but since it was already a popular folk ballad, it's likely that the tune is actually much older.
The lyrics we sing today, however, were written nearly 300 years after its first publication.
In 1856, English songwriter William Chatterton Dix was bedridden with an illness that nearly killed him.
But when life handed him lemons, Chatterton Dix made one of the most enduring Christmas carols ever; taking the melody of "Greensleeves" and writing a new song he called "What Child is This?"