The Tzenketh system was an inhabited planetary system in the Alpha Quadrant. A planet in this system, Tzenketh, was the homeworld of the Tzenkethi.
In 2259, the location of this system was labeled on a stellar cartography chart that was seen on the USS Enterprise's ready room viewscreen. The system was denoted by a purple symbol – the only system onscreen to be marked with this color. (SNW: "Strange New Worlds", "A Quality of Mercy")
The system's location was labeled in a Federation star chart that was in Fleet Admiral Kirsten Clancy's office at Starfleet Headquarters in 2399 and on the bridge of the USS Titan-A in 2401. The Tzenketh system was in or near to Federation space. (PIC: "Maps and Legends", "The Next Generation", "Disengage")
In 2401, this system's position was labeled on a star chart used by Captain William T. Riker during his attempt at finding the last known location of the SS Eleos XII. (PIC: "The Next Generation")