The harp music of ancient Sumeria.

Jack, I'm sorry, but unless you have some connection with the occult, we have no way of knowing that. You're talking 4,000 to 6,000 years ago. The musical instruments that have survived from that era consist mostly of lyres, very primitive harps, and various kinds of pipes and flutes. Since no method of notation has survived, any theories about the kind of music they played and what its harmonic structure was (if any) is pure speculation, based on listening to the music of peoples we assume to be their modern descendants and then extrapolating from there. We don't KNOW the structures of the scales (modes) the ancient Sumerians used, nor do we know whether or not their melodies were harmonized—and if so, in what manner.

Jack, I don't know what you musical training and background is, but mine comes from three years at the University of Washington School of music and another two years at the Cornish School of the Arts, a music conservatory. Early music (including speculations on how music itself got started in the first place), including modes, was covered quite thoroughly. And since I'm acquainted with such things as the experiments of Pythagoras with the monochord on up to early European music (among other things, having spent some time singing with a medieval men's group where we were very precise about the autenticity of what we were doing), I am thoroughly acquainted with such things as modes and gapped scales.

And what rings in my mind now is the admonition from more than one music professor:   "Don't try to make it more complicated than it already is!"

I think the folks on this thread are primarily interested in knowing what's going on when they encounter modal and gapped scales in folk music and ballads, what to do with them, and, if so moved, how to accompany them on the guitar or other modern harmonic instruments.

Let's not make it overly-complex.

Don Firth