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There is a long and obscure history here. I doubt if anybody knows the whole story. My opinion is that Arabic influence, via Spain, has a lot to do with it.

One might ask the converse: Why is the guitar not tuned to a G major chord? Strings 2,3 and 4 give a G major chord, so why not tune the whole instrument that way (DGDGBD)?


Flatfoot sez: Call me when 'Talent-in-a-Box' is ready to ship! -- [8{>

Got some tunes on You Tube:
http://www.youtube.com/user/flatfoot50
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My BiaB lesson site:
http://jdwolfe0.wixsite.com/learnbiab