The Cylons are a cyberneticcivilization at war with the Twelve Colonies of humanity.  Moving beyond their original limitations, the Cylons of Earth were finally able to reproduce and memory transfer and resurrection technology were abandoned and forgotten. As civilization on Earth continued to grow, a new race of mechanical Cylons were created. Roughly two thousand years after the colonization of the Thirteenth Colony, Earth's mechanical Cylons rose up. A devastating war ensued and Earth's inhabitants were wiped out in a nuclear holocaust