Nebria

Nebria was a world in the farthest reaches of the galaxy, beyond Wild Space and the Unknown Regions, that Darth Nebulous retreated to when his body was being destroyed by the Force, and after the death of Darth Nihilus. It was once a lush, unnamed forest planet, but upon the arrival of Nebulous, its landscape slowly became tainted by the dark side, and the powers Nebulous brought. He named it Nebria. Later, on 5 ABY, Nebulous was discovered by Darth Albtraum and Darth Tormenus, and together they formed the Sith Triumvirate, and made the Sith Empire. After this point, they were the only three to so much as know about Nebria.