The Great King long ago ceased attempting to police the wastelands of his Border Marches, and these debatable lands fell into the hands of petty counts, retired generals, and warlords, who constructed and then abandoned many keeps ripe for plunder.
A village where everyone goes blind sometime during puberty. What could be causing this? Perhaps something in their diet. Or some malignant gene. How would an entire village where only young childen can see function?