Kaval sviri (the Flute Plays) is a traditional Bulgarian folk song. Popularized by the Bulgarian State Radio and Television Female Vocal Choir, it was later used by composer Joseph LoDuca as the basis for the Xena fight theme, in the show Xena: Warrior Princess.
The song is also sampled in Austrian Neue Deutsche Härte band Stahlhammer's song Stahlingrad, off the 1997 album Wiener Blut.