Rajatha Prime

Rajatha Prime was lush world capable of supporting humanoid life. At least one area of the planet featured a rainforest environment.

Prior to the 4th century Rajatha Prime supported a primitive society, the Rajathans, who built monumental cities on the planet. For reasons unknown this civilization died out. Rajatha also supported avian and insect life-forms.
 * On their level of architecture and art the Rajathan civilization would seem to be roughly comparable to the Maya of Earth.

In or shortly after 2296 a group of criminals who had stolen a shuttlepod from the starship Columbia (NX-02) crashed on Rajatha. The group survived the crash but soon killed each other due to the harmonic diamonds they possessed which stimulated primitive emotions such as anger, envy, and greed, causing infighting within the group.
 * The 2296 data comes from Commander Riker at the end of the comic, earlier Picard hypothesises the shuttlepod had been on the planet for two centuries, a date in the 22nd century would be far more appropriate for the theft of a shuttle from an NX class starship.

In 2368 the ruins of the Rajathan cities, previously undiscovered due to planet's unique ionosphere effecting sensor scans, were discovered by Dr. Marjorie Devarona. She led a small expedition to the planet to explore the rare pristine site. Shortly into their time on the planet the team discovered the crashed shuttlepod and the harmonic diamonds, still in possession of corpses nearby. The diamonds immediately began to affect the group inciting debate and by the next morning Dr. Devarona was dead. As the day progressed further members of the team were found dead until only two remained; Jean-Luc Picard and Gest remained. Gest who had first discovered the diamonds and been most affected killed the majority of the others was only stopped from killing Picard be the timely arrival of the USS Enterprise-D, altered by the lack of contact with the expedition. (TNG comic: Captain's Pleasure)