Planet (The Menagerie)
From Tardis Wiki, the free Doctor Who reference
A relatively primitive and rain-sodden planet visited by the Second Doctor, Jamie McCrimmon and Zoe Heriot in the 35th century.
The planet was home to the Knights of Kuabris, human colonists from Earth who had rejected technology to live a more primitive life. Their society reflected that of Earth's Middle Ages. They built castles, kept slaves, and had travelling freak shows. (PROSE: The Menagerie)
