Zeffo was an electromagnetic wind-swept planet located inside the isolated Zeffo system which was a part of the Outer Rim Territories close to the Veragi Trade Route. It was located in the New Territories, the northernmost region of the galaxy in grid square M-3 of the Standard Galactic Grid. From space, it looked like a green- blue orb covered by large patches of white clouds. It was rich in water that also featured regions of rocky mountains and cliffs covered in grass and snow and was inhabited by dangerous fauna such as the Jotaz, Phillaks and Scazz. It was the homeworld of the ancient Zeffonians then later a small community of archaeologists and pioneers who hailed from the Galactic Republic.

The world was dotted with various ruins, ancient catacombs and tombs that was built by the ancient Zeffonians. They were thought to have died out by the time of the Clone Wars. By 14 BBY, the world was occupied by the Galactic Empire with the world being slightly scarred because of the initiation of Project Auger.