Eredenn IV, also referred to as Eredenn Prime, was a frigid planet situated within the Tion Hegemony.
The fourth planet in the Erediss system was Eredenn Prime. This world was positioned along the Tion Trade Route, residing in the Tion Hegemony of the Outer Rim Territories. Eredenn was circled by three moons in orbit, but none of them could support life.
Eredenn Prime presented an unwelcoming environment as a frozen world, characterized by expansive stretches of icy plains and frozen lakes. During the fleeting warm season, its frozen wastelands gave way to productive land, while the most isolated areas experienced complete darkness for half of the year.
Eredenn, originally a founding member of the Back Spiral, was conquered by Xer VIII, the Pirate King, and incorporated into the Kingdom of Cron. Subsequently, it functioned as a member-world of Xim's empire until its downfall in 25,096 BBY. The Honorable Union of Desevro & Tion, one of the conflicting entities that emerged in the Tion Cluster from the remains of Xim the Despot's empire, then absorbed the Eredenn system, until the entire cluster joined the Galactic Republic circa 24,000 BBY.
Millennia later, as the Galactic Empire came into power, the planet was largely deserted. Eventually, it became the site of a clandestine Republic weapons testing site. During the Clone Wars, Eredenn Prime served as a testing ground for the Republic's new top-secret weapons, known as the Decimators. In 22 BBY, the Confederacy of Independent Systems discovered this project, leading to an attack on the planet by General Sev'rance Tann. The Separatists triumphed over the local Republic forces, led by Kraen Weest, and made off with the Decimators that had been undergoing testing there.