The Vega System was a binary star system, meaning it had two suns. Vega VI was the sixth planet in this system. The Vega System was conquered by the Daleks during the invasion of Mutter's Spiral and the Second Great Dalek Occupation. It was exploited for its resources, the Veganite in particular. (AUDIO: Invasion of the Daleks)
Human historians in the post-Time War universe, following the Siege of Trenzalore, acknowledged Vega IV as a world which had fallen to the expanding Dalek Empire. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)