The Tomb of the Ancients, also known as the Death Capital, and in Bara Magnan Makuta dialect, VoxMorte'Carena, translation meaning Bright Capital of the Dead, was found(ed) by the Exiled Outcast and founder of the Brotherhood of Makuta, Makuta Erodar. Makuta Erodar, now exiled to an unknown dimension, rallied with the Great Spirits in a council. He decided to make a grand grave for them, a marker of their glory. They denied it, saying they had no possible way of dying. Erodar, frustrated, secretly killed several Great Beings and said now it was possible for the tomb to be built. Finally, they let Erodar construct it with ease using his Olmak. He created a tomb incredibly large that it was practically a city with tombs already filled and some empty. He hoped no Makuta would truly ever understand it, so he mixed a Makuta dialect code with Bara Magnan and called it VoxMorte'Carena.
The Shadow Council is formed
During Erodar's exile, he started taking over Scrap Matoran cities across thge void to unite them and build inter-universal ports. He helped defend them from Void Dragon, a nearly impossible-to-kill species of Kanohi Dragon that can phase out but still successfully attack. At one village he found Makuta Teridax, but the one from Spherus Magna. Evidently Teridax had been exiled by the Great Beings for beginning to have shadows in his heart rather than watching over the matoran all day. Erodar fully corrupted this Teridax, changing him from white to black, and together they joined the powerful and dark matoran outcasts to form the Shadow Council inside the Tomb of the Ancients.
Later on, Brutaka was sent to the Outer Remnant to retrieve powerful and legendary weapons from a deceased Great Being inside the Tomb. However, Brutaka was captured by the Shadow Council and was made a captured resident of the Death Capital. He spent nearly five years imprisoned until he finally was able to break free and retrieve the weapons needed to complete his mission.
Brutaka finally managed to grab all of the required items, but then he was locked in battle with Erodar, he battled fiercely with the legendary weapons but seemed to be weaker than the Great Makuta. In a last ditch effort, he damaged Erodar's mask in a spot that prevented his mask from teleporting into the Outer Remnant. He then opened a portal and teleported Erodar to an unknown dimension. Erodar still lives but nothing is known about him.