Telos IV, commonly known as Telos, was a planet of the Outer Rim of the galaxy.
The planet was a military stronghold for the Republic during the Jedi Civil War. Knowning this, a Sith Fleet attacked Telos and destroyed the planet's surface, making it uninhabbitable to anyone.
With the Ithorians being well-known terraformers, the Republic hired them to rebuild Telos IV and restore it to its state before it was destroyed. This plan was seen through aboard the Citadel Space Station. The Ithorians lived there while they worked on the planet.
The restoration of Telos IV was almost complete, until the Sith Fleet returned and destroyed the Citadel Station.