There are 5092 novels set in the Middle Ages
Which is why my (hypothetical) mystery novel will be set during the beginning of the Roman colonization of Britain. And the detective is a druid.
Wait, what's that you say? It sounds like Cadfael or The Name of the Rose with white robes and hard-to-pronounce names? Dammit. Yeah, well... You and my husband can go back to reading Conan Doyle; I have genius to tap into.