This is a very dangerous area early in Chapter 11 when Behemoth Kings are likely to kill the party, because they are all over the place. It's not strictly necessary to come here early on, though some Treasures are to be found here, and completing Mission 05 unlocks the Waystone in Vallis Media. If you do have to fight any Behemoth Kings, try to get a preemptive strike, and Launch them to finish them off before they can stand and become truly dangerous. Rangdas on this Map can summon Behemoth Kings.