Hadar

Hadar, also known to Earth's astronomers as Beta Centaurus, was a star about a hundred twenty parsecs from Earth. The sixth planet in the Hadar system was S'Arl, home to the Tzun. Around 23,000 BC, the sector of space Hadar occupied was controlled by the Darklings, until they were defeated by the Tzun. The Hadar system was the centre of the Tzun Confederacy until their war with the Veltrochni in the 22nd century. The area became part of Draconian space in the 26th century, after what Bernice Summerfield subjectively referred to as the most recent Dalek war. (PROSE: First Frontier)

Behind the scenes

 * Hadar is actually known as Beta Centauri, not Beta Centaurus as the Seventh Doctor claims.