The Valley of the Dark Lords on Moraband served as a vast necropolis, housing numerous monuments that functioned as crypts for the deceased Dark Lords of the Sith. The most imposing structure within the valley contained the final resting place of Darth Bane, the originator of the Rule of Two.
Around the time of 5000 BBY, the schism within the Jedi Order precipitated a civil conflict. In this war, the Jedi and the newly established Sith Order, once united by the Force, clashed for dominance. The Sith suffered defeat, leading them to escape from known space. However, unbeknownst to the Jedi, the Sith found refuge on Korriban, a planet characterized by red sands that would later become Moraband. There, they secretly rebuilt their strength, biding their time for a future opportunity to strike. As the Sith Order expanded, they erected colossal temples and tombs in a region of Korriban known as the Valley of the Dark Lords.
During the era referred to as the dark age, the Jedi-Sith War erupted. The Jedi triumphed over the internally divided Sith, effectively crippling the dark order. However, one Sith, Darth Bane, survived and subsequently established the Rule of Two. He holds the distinction of being the last Sith Lord to be interred within a sarcophagus in the Valley of the Dark Lords before it was abandoned.
In 19 BBY, during the Clone Wars, Yoda, the Grand Master of the Jedi High Council, was dispatched to Moraband by the Force Priestesses as a crucial step in his quest to uncover the secrets of eternal consciousness. Upon arrival, he encountered several Sith spirits, including that of Darth Bane. As he progressed deeper into the Valley of the Dark Lords, he was confronted with visions conjured by Darth Sidious, the current Dark Lord of the Sith, who attempted to sway Yoda to his side in order to secure victory in the Clone Wars.
The Sith Lord Darth Sidious referenced the Valley of the Dark Lords as he recounted Sith history within his literary work, The Secrets of the Sith. He communicated that he perceived the voices of his forerunners calling out to him from Moraband while he was on Exegol in the Unknown Regions, presenting him with their sinister knowledge. As the Sith Eternal's military force, known as the Final Order, seized control of Moraband, Sidious intended to respond to these calls. However, Sidious met his demise alongside the Sith fleet during the Battle of Exegol shortly thereafter.
The Valley of the Dark Lords initially appeared in the episode titled "Sacrifice," which was part of the sixth season of the animated television program Star Wars: The Clone Wars. This rendition of the valley drew significant inspiration from the one depicted in Star Wars Legends, which was first introduced in the 1994 comic book Tales of the Jedi – Dark Lords of the Sith 3.