Koinonian homeworld

From Memory Alpha, the free Star Trek reference.

The Koinonian homeworld is home to two sentient species, the extinct corporeal Koinonian and their non-corporeal neighbors who still live on the planet.

The corporeal Koinonians destroyed their entire race and ravaged the planet in the Koinonian Wars and left behind only dust and rocks on the surface. Some underground caverns, the Ceremonial chamber being one of them, and tunnels still remained intact but the rest of the planet is completely barren.

The USS Enterprise-D did some archeaological research on the planet in 2366 and discovered that it was indeed the homeworld of the two species. Further sensor scans of the planet revealed the following data:

The planet can be classified as M-class, type 4 and is considered only marginal suitable for Human habitation. The radiation factor was measured at 6 and the result of scans for minerals were unreliable, possibly due to the radiation. (TNG: "The Bonding")