The Diminished 7th Chord could not have existed prior to the temperament of the scale. It arose from the Harmonic Minor Scale which was created post-temperament. They deployed this scale almost immediately after a chosen temperament was accepted. It was basically around the time of Johann Sebastian Bach. In fact, Bach himself was involved in the temperament of the scale. Once that was completed, the 12 so-called "Minor Keys" were created giving us now, 24 keys. Ergo, we get his songbook, "The Well Tempered Clavier," in which he wrote music in all 24 Major and Minor Keys in order to demonstrate their usage. This man helped change musical history altogether, and obviously enough, was a genius beyond comparison. ... https://www.youtube.com/watch?v=ufz-v2vHtSY

... https://www.youtube.com/watch?v=lFp6blWd83k