Harankast was a world inhabited by the Ranfo.
At some point a group of human colonists landed and thought the planet so beautiful that they decided to stay. The two species lived in harmony for a while, with Ranfo keeping to the countryside while humans built cities.
Humans drove water-powered cars until Joseph Manver of Manver Autos started selling faster but also very polluting cars. To convince people to buy his cars, he created robotic Spy Flies transmitting a Brainwashing Beam. The Tenth Doctor discovered this and disabled them, after which the beam wore off and Manver was arrested. (COMIC: Exhausting Evil)