Here, though, the source of horror is not the scary dark-skinned Other, but rather the past. The things our ancient forebears used to know and do, and the possibility of those hideous rites surviving or resurfacing into the present day.

So, foundational folk horror which I have somehow never heard of! Thank you for the pointer. The story may or may not live up to it, but "The Watcher by the Threshold" is an incredibly evocative title. (I'm so sorry about the eye dialect.)