Earth is a world populated by humans. Earth's history is intertwined with its sister planet: Cybertron. Earth and Cybertron share a lot in common. This involves Unicron the bringer of destruction being Earth's core while Cybertron has his brother Primus as its core.
History[]
Transformers: Robots in Disguise[]
Optimus Prime sent Bumblebee to Earth to assemble a team capable of hunting escaped Decepticon prisoners.