Libro de Los Juegos
en.wikipedia.org
en.wikipedia.org
But not, it is about a medieval book about games from kingdoms from spanish territory.
Seriously though, Spain had great monarchs up until (and including?) Charles V.
https://www.ancientgames.org/wp-content/uploads/Alfonso-Xs-B...
https://eprints.ucm.es/id/eprint/39444/1/Libro_de_axedrez_da...
As a Spaniard with no formal studies in literature/old manuscripts/etc I need to note that I find it very hard to read the typography in the book, but it does seem similar to other very old books I've seen before (many vertical parallel similar strokes).
I tried with the image in page 12 and, even if most words should ring a bell (my own family name, places near my hometown), it was really hard.
I guess the f is some form of long s, so Caftela should be "Castela", now Castilla. Still "Affonffo" is puzzling how could possibly be Alfonso. It's interesting the use of ^ over vowels to indicate that an n or m follows in Côpoftela, that I guess it's Compostela. Also ç for Murcia. Also "outroffy" should be almost impossible to identify as "otrosí" ("also") for modern speakers. Painful.
Still, it's worth mentioning that El Quijote was less than three centuries later and perfectly readable today. There are some expressions that would be weird for us, but most of the text is very clear. Actually, I bet we could hold a conversation with Alfonso X. For comparison, I've read somewhere that the English of that time would be unintelligible for modern speakers.
Yes, while I found El Quijote sounding obnoxious I could understand most of it when I tried reading it. Definitely way too slow so only went a couple of pages in, but agreed I was happy to be able to read it. I wonder whether having literature at this age, and a language that is mostly spoken as it is read, and a pretty unified country contributed to the stability of the Spanish language/pronunciation.
It is not a ^, it is a ~, and it is the way that the ñ and the Portuguese ã and õ were developed.