Valley of Judgement

The is a location most popularly known for having the fabled Eye Medicine Plant: a medicinal herb that works well for eye strain. The valley itself, however, is treacherous and is noted to be a dangerous place for even jōnin-level shinobi. Thick mist makes it near impossible to see except for those with powerful dojutsu, like Byakugan or Sharingan. The valley is inhabited by strange humans with no eyes who walk on all fours. Kakashi notes that they have discarded their eyes after what could be hundreds or thousands of years of living without sunlight. They appear able to use kunai suggesting they may have once been shinobi. It's noted they're unable to survive outside the valley.