The Tau Cygna system was a planetary system that was located in the de Laure belt, over five thousand light years from the Sol sector. Its primary star was Tau Cygna.
In the late 23rd century, the colony ship SS Artemis landed on Tau Cygna V, the only planet in range suitable to do so. The survivors built a colony which lasted for nearly a century. However, under pressure from the Sheliak Corporate, the colonists were relocated to a new home. (TNG: "The Ensigns of Command")
The system map used for Tau Cygna was first used as a map for the Maxia Zeta system ("The Battle") and was used later for the Omicron Theta star system ("Datalore") and the Mira Antlia system. ("Conspiracy")