The Votans ("voh-tans") is the collective name for the alien races that invaded Earth in arks. They are not a single species, but a collection of seven different alien species who evolved on separate planets in the Votanis star system.
The Votanis star system was actually a binary star system, composed of the stars Vysu and Solus. Vysu was orbited by two habitable planets, Daribo and Irath, each of which had one habitable moon. Solus was orbited by one habitable planet, Casti. The Indogenes and Castithans evolved on Daribo, and the Castithans later colonized Casti (hence its name). The Irathient, Sensoth, and Liberata evolved on Irath. The gas giant Gula's orbit is unknown, as is the Omecs and Volge homeworld Omec.
The different races banded together to flee their star system when it was destroyed in a stellar collision, and ultimately arrived at Earth. The Votanis star system was destroyed in a stellar collision 5,000 years ago, but the millions of Votans who fled in ark-ships made the long interstellar journey in hypersleep.