In the 23rd century, the planet was considered a prime target for colonization by the Federation, as it had a moderate climate and almost anything could grow in the rich soil. Unfortunately, the planet was also discovered to be bombarded with Berthold rays, which prevented any livestock from living on the planet for longer than seven days.
In 2264, a colonization expedition led by Elias Sandoval made planet-fall. Unlike previous colonization attempts before them, they were able to survive the harmful affects of the berthold rays when they were infected by spores from the local spore plants. In addition to protecting them from the Berthold radiation, the spores gave all the colonists a sense of well-being and perfect health. But the side effect of the spores's infection was, in infected persons, loss of initiative and a placidity that bordered on the lackadaisical. It ultimately took the strong emotions of a sapient being to override and countermand that effect.
In 2267, the USS Enterprise arrived in orbit to ascertain the fate of the colonists. When they discovered the effects of the spores, Captain James T. Kirk and Commander Spock were able to free the colonists, and evacuate them to Starbase 27. (TOS episode: "This Side of Paradise"; novel: Crucible: The Fire and the Rose)