Dhorak Keep or Dhorak's Keep was a location in older versions of Mount&Blade, making its first appearance in Warrider (version 0.202) and being removed in version 0.894.
Despite it being removed, it's still in the game files and can be activated via editing.
In Warrider[]
In Warrider the location is hidden by default. As implied from a conversation with Borcha, it is supposed to be a prison. When entering, the scene is a plane surrounded by large hills at the edges that has a very basic building structure - four walls and no roof - in its near right-hand corner, and an npc called Keepmaster Gruham, apparently the local overseer.
Outside of possible unplayable quests, there is nothing to be done here.
In later versions[]
In later versions Dhorak Keep became a castle inhabited by bandits, led by Rolf, the Baron. In some versions the Keep could be attacked. In others, it could be entered to hire bandit troops. After the keep was removed, Rolf was promoted to a potential player companion.