Erden is a planet that is home to the Erdenites in 'Get Animated'.
They are variations of Humans from another universe, not alternate. It is also known as a Phantom planet for it just appears when you least expect to find it or life.
It was a planet for of godlike beings, revered for the gifts and powers they possessed, but one day Dagon rose up and things took a turn for the worse, using his son Metroy to either turn them into Esoterica or ending them on the spot.
Eventually, Dagon's body and power were severed from each other and he was sent far away to the Earth and we all know that story. He was banished from Erden for what he did, which left only Metroy as the sole survivor and inhabitant of the entire planet.