Rhen Var has a frozen surface, somewhat more mountainous than that of Hoth, but is still covered with snow and ice. Rhen Var was once a fertile paradise filled with vegetation and wild life. Millions of years ago, an atmospheric cataclysm turned it into an icy hibernate surface. Ancient Jedi monuments are buried beneath the surface of Rhen Var.
After The Great Sith War (4,000 BBY), Ulic Qel-Droma sought refuge on Rhen Var, and he is buried there which held the secert to defeating the Dark Reaper. Along with the tomb of Qel-Droma, there are great chambers of ancient texts, some that pre-date the Old Republic and the Jedi Order. In one or more of these chambers is believed to be a superweapon built by an ancient race. The weapon is rumored to have the power to wipe out all life in the galaxy and wash it clean.
During the Clone Wars, the Confederacy of Independent Systems, or the CIS, seized Rhen Var with an army so large that the Republic base had to evacuate the planet. Obi-Wan Kenobi informed the Jedi Council about the capture of the planet. After the liberation of the Kashyyyk moon Alaris Prime, the Galactic Republic retook Rhen Var.