Metralubit

Metralubit is a planet that was settled by humans in the fifty-eighth segment of time and is located in the Fostrix galaxy.

There were at least 6 civilizations on Metralubit. During the first civilization, the Darkness found it and started the feeding cycle. Each civilization was able to last around 2000 years before The Darkness made it plunge into chaos. The Darkness was able to feed on the carrion and death that was created and then went back into hibernation.

The Yelphaj Civilization
While it also fell almost overnight, the Yelphaj civilization was noted for weathering plague, flood, and famine without losing stability.

The Helducc Civilization
The Helducc civilization had a population of approximately 3 million, and spanned 40% of the planet. It was destroyed in a conflict sparked by a rivalry between two of its rulers. It was the immediate precursor to the civilization that occupied Metralubit during the Doctor's presence on Barclow.

The Sixth Civilization
The sixth civilization was the one extant on Metralubit at the time the planet was visited by Romana and K-9. It was a constitutional democracy, ruled by a Premiership. Premier Harmock was the incumbent at the time, ruling from the capital city of Metron.

The sixth civilization was developing at the same rate as the first five civilizations. Progress moved slowly and the planet was polluted and dirty. Eventually, Menlove Stokes' cryogenics chamber was found. By extrapolating the knowledge in his mind, they were able to make great leaps technologically. As well, they were able to create the Femdroids from Stokes' memory of K-9. These Femdroids, being more efficient and intelligent then humans, were able to see the pattern of destruction.

The Femdroids decided the best choice of action would be to send most of the humans to Regus V. The Darkness would be then distracted by a war on Barclow. Eventually, The Darkness would move in to feed, when Barclow would be blown up, destroying the Darkness.

Unfortunately, this plan was stopped after meddling by Romana, K-9 and Menlove Stokes. (MA: The Well-Mannered War)