Here, try the Historical Novels page
. They've got listings for thousands of the things, split up into time eras. And they separate out the mystery stuff so if you want genfic or sf or whatever, it's easier to find.
PS. If you collect the publisher promo freebies, you may already have Ruth Downie's Medicus
, as it's been offered free twice and I think it was a B&N Free Fridays feature.