Erdelezi. The Wikipedia article on this song says, ""Ederlezi" is a popular traditional folk song of the Romani minority in the Balkans.

"The song got its name from Ederlezi which is a Spring festival, especially celebrated by Romani people in the Balkans, Turkey and elsewhere around the world. This holiday celebrates the return of springtime. Ederlezi is the Romani name for the Bulgarian, Macedonian and Serbian Feast of Saint George."

There are some nice recordings on YouTube (but when I tried to post this with a link earlier today, it vanished into the ether, so now I'm trying it without the link).