Thanagar

History
Thanagar was a slave world in the empire of the planet Polara millennia ago. According to legend, a slave named Kalmoran slew his keeper and organized an army of his fellow Thanagarians, and led them in attacking a Polarian garrison, seizing their starships and using them to attack the other Polarian slave worlds. After defeating the slave planets, Kalmoran's armada attacked and razed Polara, ending the Polarian empire. Kalmoran returned to Thanagar, where he built a great city and lived there as his home planet's ruler. Generations after Kalmoran, the Thanagarians built a vast interstellar empire and adopted policies of aggression and imperialism.