In the phrygian mode

Not too long ago I was puzzled to hear my father tell me that a lot of Greek folk music is in the key of E. How could he know the precise key of a folk song with so many variations in so many parts of the Greek-speaking world? It quickly dawned on me that he meant that it was in what we now call the phrygian mode, which spans the octave between any two E's on the white keys of the piano. Here is an example from one of the Aegean islands: