Necropolis is a planet in Sector 3502 that was chosen by Thaal Sinestro to be "New Korugar", to replace Korugar, on account of the fact that the original had been destroyed by Volthoom, the First Lantern.
Initially inhospitable and volcanic, the planet was partially tamed when Sinestro sealed himself into its core and used the power of Parallax to regulate the mantle. Though the climate was still hard, the Sinestro Corps, led by Soranik Natu, worked to help the Korugarans.
Their greatest challenge came when the Red Lantern Corps brought a terraforming engine to the planet, with the intention of killing every Korugaran in the massive change it would cause, out of revenge on Sinestro. However, with forewarning, the Sinestro Corps was able to steal the engine, and activate it safely, giving the Korugarans an independent future on a pure world and letting the Corps go elsewhere.