History and specifics
Kuban was uninhabited, barren, and rocky.
In 2270, Pavel Chekov participated in an experiment under hypnosis to see if he could imagine himself as Harry Mudd and provide clues to his whereabouts. Chekov suggested Kuban, but also the planet Sarai in Sector 29G. The starship USS Enterprise proceeded to Kuban, but found no trace of Mudd there. (TOS - Mudd's Angels short story: "The Business, As Usual, During Altercations")