Maradnias

was a planet.

The Sixth Doctor unintentionally exarcerbated a civil war, resulting in the death of billions. After helping restore the Lux Aeterna, Sadok and Lillith altered events so the Doctor's visit there never happened, undoing the war. (PROSE: The Quantum Archangel)

In the 108th century, the capital of the Union was on Maradnias. (PROSE: The Crystal Bucephalus)