Erghen Diado first appeared on the now-famous album Le Mystère des Voix Bulgares in 1975, performed by the Bulgarian State Radio & Television Female Vocal Choir. There the composition of the song is credited to the album’s producer, Paul Cellier, but it was in fact written by the Bulgarian musicologist and composer Petar Liondev.
On the Mystère album the song is subtitled Song of Schopsko – a reference to the diaphonic (two-voice) singing style common in the Schoppe region around Sofia. But translations of the main title run along the lines of Bachelor Grandpa or Unmarried Old Man. You’ll find a meticulous translation of the whole song here