Earth is a little blue planet at the unfashionable end of the western spiral arm of the galaxy.
It's not a great place to live, being beset by terrorist organisations, rogue paramilitary groups, corrupted AIs, supervillains, extradimensional despots and two separate species of alien shapeshifters. Much of this is due to the presence of Ore-13, a potent fuel source with mystical applications seeded on the planet by an alien during the ice age.
The main life-forms inhabiting the planet are humans. Sucks to be them.
The Dire Wraiths arrived on Earth at some point during the 1800s.
Cybertronians started arriving en masse on Earth in 2001, applying infiltration protocol as they engaged in covert warfare over the Ore-13 deposits. In 2005 the Cybertronians abandoned infiltration as the Great War came out of the shadows.
In 2008, the entire planet was subject to a massive invasion by the alien tyrant known as Megatron. Billions died with New York City being virtually destroyed before the Autobots defeated him and his forces.
In 2016 following repeated Decepticon attacks on Earth, Optimus Prime took matters into his own hands by annexing Earth into Cybertron's Council of Worlds. Humanity, however, took this as a threat, and responded by reactivating the disbanded G.I. Joe and creating the Mobile Armored Strike Kommand.