Earth
Planet the Ark crashed on 4 million years ago. Its main sapient inhabitants are known as humans, earthlings, or homo sapiens. The Decepticons have been known to refer to humans as "fleshlings" (comic) or "flesh creatures" (cartoon).
4 million years ago, the Ark, containing combating Autobots and Decepticons, crashed onto
the planet Earth in the Sol solar system. The Decepticons realized the vast energies that
could be taken from the planet and sought to take over the world. But while the Decepticons
managed to get enough energy to supply their operations on Cybertron, they found themselves
losing ground on Earth. Twice, Megatron attempted to harness the power of the planet's
molten core, but failed. His transfer of the planet Cybertron into Earth orbit nearly tore it apart,
but the plan was foiled before total destruction could take place. At one point, the humans
effectively evicted the Autobots from the planet, but upon their unexpected return, they were
welcomed back. By 2005, Earth had
become an Autobot stronghold, and by 2006, the humans had sufficient technology to help the
fight, if not take on the Decepticons by themselves.