Hello there!
We actually have a book list that is compiled and maintained by our flaired users. Given that you didn't really specify what sort of Medieval History you are looking for, I will just link a couple that I think would be the sort of thing you are looking for below. If you want some more info, the bibliography sections contained in each of these sources should let you hit the ground running on the relevant topics.
Relevant Book List Sections
I'll also note that there is a very brief section on Medieval Philosophy in the History of Philosophy Section