I have a HUGE playlist of some of my favorite recordings on YouTube, for anyone interested! A lot of 12th and 13th century stuff, Troubadours and the like. There's also some early polyphonic choral music from that same era. There's even some Cathar music from that era in the mix!

The playlist doesn't look that large but it's actually very long since there are several complete albums in there.

https://www.youtube.com/playlist?list=PLZZqxGNZE7hZR3HHUvl_eO-yiwy6WAIwY

For those not familiar with actual medieval music, it's extremely different from what passes for medieval in games and movies (most of that is either Celtic or Renaissance). The compositions were often surprisingly sophisticated. It's easy to see the middle ages as a barbarous age when the arts were stunted but what we see instead is a rich culture unlike anything before or since, capable of highly sophisticated expressions. It's a world that was swept away by the Black Death and the rise of mercantilism and industry, in some ways lethally primitive (such as their understanding of infectious diease) but in many respects just as capable as any of their modern counterparts. The Portative, arguably the direct ancestor of the accordion but a distinct instrument in its own right, is a wonderfully expressive and sophisticated instrument.

As a bonus, here's a video of a trio performing a very soulful jam on a medieval Portative, a chinese Sheng (mouth organ), and the Hang, an instrument invented in Germany in the year 2000:
https://www.youtube.com/watch?v=bD8sXqdjCFg