Tulak Hord was a Dark Lord of the Sith that ruled sometime in the ancient past of the Sith Empire after they had begun to use lightsabers, some time between 6,900 BBY and 5,100 BBY. Hord wore a claustrophobic black mask, making him a fear-inspiring sight.
It is unknown how Hord died, but his power was so considerable that a burial chamber was built in his honor in the Valley of the Dark Lords on Korriban. In later years, both Darth Revan and a Jedi known as "the Exile" visited his tomb in the times of the Old Republic.
Now the new Dark Lord of the Sith comes here for guidance and only he is permitted to visit his grave. If you want to visit it, you better be careful. The tombs are guarded and monsters are often spotted in the valley itself. So enter at own risk!