The inhabitants of Errikang VII were previously acquainted with Q; Vash was nearly killed visiting the planet while in Q's company. (DS9: "Q-Less")
This planet was only mentioned in dialogue.
According to StarTrek.com, the primary of the Errikang system was named Errikang. StarTrek.com gave the pronunciation for Errikang VII as "AIR-ih-kang" ; ; however, according to the script pronunciation guide, the pronunciation was "ERR-i-kang".