Olympia
Olympia is the now dead world where the pod of the primarch Perturabo of the Iron Warriors landed. Before it became the barren dead world it is today, Olympia was once a mountainous planet where the population resided in large city states throughout the planet. One of cities was called Lochos where Pert's adoptive father resided.
History
Before the coming of Perturabo and the Emperor, Olympia was ruled by several warlords who ruled sover the city states around the desolate planet. After Perturabo smashed into the mountains after being flung from the Emperor's laboratory, he was adopted by the powerful warlord Dammekos. Pert was a pretty emo kid, not showing any love for anyone despite his father the Tyrant of Lochos spending a lot of time with him despite getting nothing in return. What a nice chap! Then the emperor came with a whole bunch of cool toys and Perturabo decided to join the emperor and play with his new legion until his father was killed and Olympia was claimed in the name of the Emperor. Later on, Fucking Horus told Perty about the people on Olympia rebelling against Perturabo. He then decided to give everyone an order. Fucking stop rebelling or get gunned down by fucking Adeptus Astartes and all the cool siege weapons the Iron Warriors loved so much. Turns out, a few million people really wanted to see what a bolt shell looks like as millions of Olympians were slaughtered by the Iron Warriors. Horus then swayed Perty from the Emperors light, saying that killing your own people in the millions was the right cource of action. During the end of the Horus Heresy, the Iron Warriors decided to set up camp back on Olympia for two years whilst the Smurfs and Imperial Fists attacked them. The Iron Warriors then had to evacuate as all the missile reserves and other cool exploding things exploded, turning Olympia into a barren wasteland. It was then renamed Perdita. Also, there may or not be a lot of Necrons under Olympia/Perdita.