- "Hey, we don't serve their kind in here!"
"The meatbags! They'll have to wait outside!"
- ―A bartender on Cybertron
Cybertron was a freaky machine planet somewhere on the Outer Rim of the galaxy where the fucking Transformers lived. The planet was about the size of Coruscant, but it was metal and machines all the way through (Coruscant only had a few miles of machines before you hit the boring lower levels of the crust). In fact, Cybertron had large holes carved in the surface of the planet, and there were no handrails. Imperial engineers used this as the basis for most of their large-scale creations, like the Death Star.
There were no organic beings on Cybertron, only robots, but for some reason, there was a whole ecological system of animal robots, like robo-possums, robo-kangaroos, robo-elephants, robo-bedbugs, robo-pufferfish, robo-platypuses, and most threatening of all, the robo-candiru, a tiny robot that lives in rivers and latches onto your penis. Any organic beings that visited the planet were faced with a horrible system of Jim Crow laws. In fact, the only thing Cybertronians hated more than organic beings were B1 battle droids, which they considered a racist parody of a robot. However, despite their fierce organophobia, many of the native Cybertronians secretly dressed like humans and gathered together in cabarets, singing songs about eating and pooping and having sex and other aspects of organic life.
Cybertron never participated in any of the galactic wars (their starfighter pilots were actual starfighters, so they'd have an unfair advantage) or made contact with the Galactic Republic (except for Darth Megatron). Whenever somebody discovered Cybertron's location, they just fired up their planetary rockets and moved the planet somewhere else. Zonama Sekot did the same thing, but without the robots.