The Bastion is a sub-region in Dowdun Reach.
Getting in
It is notable that at the top of a long winding mountainous pathway from The Nexus, you'll be able to fight the Black Knight Titan and gain access to the door to the Umbral Sands. Like other areas in the region, there is a nodestone to travel up and down to the top, but it is only accessible once the barrier is deactivated.