Nice summary! I've often read about the legend of Prester John, as it crops up from time to time in various historical writing.

But I've never read such a well presented overview. And I was unaware of some of the intricacies.

Thanks!

P.S. Where you write about the world being dark and needing hope, I can't help but think that the people whom medieval European powers were fighting over the Holy Land felt that things were already quite hopeful enough. It's not so much the world felt things were hopeless, but that a small part of it did.