The Magma Caverns were a labyrinth of tunnels, created by the lava rivers from the several volcanoes of Saleucami. It was placed under the capital city.
During the Clone Wars, the Dark Jedi Sora Bulq installed a Cloning Complex in order to create an army of Morgukai clones. It also was a Separatist base to many Confederacy characters, such as the Anzat Rath Kelkko, the last true Morgukai Bok, the Dark Jedi Tol Skorr and Sora Bulq himself.