The Obsidian Union is a collection of several Sith Houses run by different Sith Lords. The organization is not as bold in its conquests and prefers to remain hidden in the shadows of the underworld. An alliance was first formed with them while the Houses were under the rule of Darth Groznii. After only a few years, Groznii became mad and tried to disband the Houses and their Sith Council. In the ensuing war, Groznii was all but defeated and the Council rebuilt their Houses and the Union was preserved.