Empire of the Eternal Star
A successor state to the Empire of the Sun that came to dominate the galaxy for over ten thousand years through superior Horizon Drive technology and large-scale terraforming.
From roughly 17,000 BAF the Eternal Star expanded rapidly, introducing nearly every currently known race to the galaxy. Its Horizon Drive remained a closely guarded secret until a Korgen revolution seized and reverse-engineered it around 6,000 BAF. In 5,500 BAF a Korgen fleet struck the imperial capital, ending the Eternal Star's rule and opening interstellar travel to the wider galaxy.