Phemis was a relatively unimportant planet located in the Core Worlds region of the galaxy, inside the Corellian sector. Notably, Phemis was unique as the exclusive source of rubat crystals, a variety of kyber crystal. These crystals were traditionally utilized by the Jedi Order in the construction of lightsabers during the era of the Old Republic. The planet's difficult environment contributed to its low population density. The total population was around ten thousand, primarily consisting of individuals in mining camps and a military presence.
Early in the Old Republic's history, Corellian explorers initially found Phemis. Nevertheless, the Jedi Order possessed a long history of mining the area for rubat crystals. Consequently, the Senate designated the crystals as a protected resource, thereby restricting subsequent colonization and mining endeavors. During the Galactic Empire's reign, the prohibition was upheld, and possessing the crystals became unlawful, although not for the benefit of the Jedi.