|Founded||5 Temporal 8784 GE|
Penumbra was founded late in the God Era by illithids of the moon Ráglauth. They built a lab over an entombed living primordial named Axinite. This ancient being served as a massive storage tank for psychic energy. It was a source for psionic leeching - the draining of psychic energy from one being and using it to restore your own. Later, this primordial was opened up and a crystal forge constructed inside its chest cavity. In this Axinite Forge, were built the Silver Mirrors. These teleportation devices would be the salvation of the illithids, saving them from a starvation they brought upon themselves.
Penumbra is also where the first Dromites were created. On 22 Bloom 9024 GE, similar to how psychic energy was drained from Axinite's body, the Creation Creed went a step further, stealing a part of his life energy to create a new race. In so doing, Axinite planted his own seed of retribution in the Dromites. He fortified their minds with a hive mentality, making them immune to certain psychic viruses and when working together, able to resist mental control; an obvious problem for their illithid masters.
When the formation of the Suellk Empire, Penumbra became its capital (1945 LE - 145 HE). Heavily debated in the Psycharum, the War Creed successfully made their case that victory would be assured if leadership was near the action. Thus after taking control of parts of the world Ghífthauk, the empire's capital was moved to the captured githyanki city of Incarsabec.
In the Incarsabec Rebellion (1531 HE - 1544 HE), Penumbra was depopulated by a virulent psychic virus. Unlike most other holdings that were caught up in this civil war, Penumbra remained untouched by military actions. Never breached in their history by enemy forces, the city had no defense against their enemy's use of psychic viruses. These would wipe out not only every sentient being in the city, but also swept the countryside of sentient life. Penumbra and much of entire moon became devoid of sentient life, an eden for wild beasts and animals.