You know, that's a great question. I stopped reading books about flamenco history a vey long time ago because I really felt that most of the books I happened upon felt completely anecdotal, or they felt very biased to me. And of course we just don't know exactly how flamenco evolved before a certain part because there is no record. I suspect that there is way more information now than there was when I stopped looking, and there has absolutely been tons of research on the parts of flamenco history that are documented. So I'll ask around! Do you read Spanish, or do we need something in English? (I'll look for both and ask some friends).