Yeah, the slip about guards I meant the reinforcement guys from Tanigakure :P.<br/><br/>Anyways I go edit the post about true red eyes then (my bad about not remember village history, I imagined it older). The five kages would know the legend of the true red eyes as it predates First Shinobi War (perhaps only known tale scroll regarding Sage of Six Paths and even then submention is vague and hints of a missing scroll which has full tale). The red eyes were active in first shinobi wars and they are well aware of brutal effiency what that bloodline provides to the user (and madness with it).<br/><br/>If speaking of importance of discovery could be compared to discovery of Rinnegan as no one really know what true red eyes are capable (besides basic info that it does not create madness and the red eye state is permament).