Sargon's homeworld

From Memory Alpha, the free Star Trek reference.

Sargon's homeworld, 5000 centuries after the Cataclysm

The chamber deep beneath the destroyed homeworld, from where Sargon has long kept watch in hopes of space voyagers

Sargon's homeworld was a planet hundreds of light years past the limits of Federation exploration in 2268. Originally Earth-like (though much older), its atmosphere was ripped away by a cataclysmic war fought half a million years before the USS Enterprise arrived in orbit. Its surface had since been uninhabitable.

Eleven survivors of that great war created a shelter 112.37 miles below the surface. This vault was constructed of material harder and stronger than anything Commander Spock had measured at that time; its atmosphere (perhaps arranged especially for the landing party) was "a fraction richer in oxygen than usual".

Originally humanoid, the eleven surviving specimens of Sargon's species placed the essence of their minds into spheroid receptacles. In 2268 only two spheres besides Sargon's still contained a living mind: that of Thalassa, Sargon's wife, among the five spheres kept on the lower tier; and that of Henoch, a member of the conflict's "other side", on the upper. (TOS: "Return to Tomorrow")