"During the opening battles of the Mandalorian Wars, the Cathar were nearly destroyed when an army of Mandalorians beseiged the Cathar homeworld. The Mandalorians systematically slaughtered the Cathar population as their Basilisk war droids swept across the planet. Only a few Cathar escaped the slaughter, fleeing to Republic space until the war had ended."
Cathar is the homeworld of the Catharspecies which it shares its name. The planet was a battlefield during the Mandalorian Wars, and almost the entire Cathar species was massacred. The Republic eventually drove the Mandalorians from the planet, but it was all but abandonded due to the devastation. Although the planet officially belongs in the Republic, the Cathar relocated to the planet Rendili because of their homeworld's hostile war aftermath.