Tzenkethi space was the area of space governed by the Tzenkethi in the Alpha Quadrant. It shared a border with Federation space.
In 2371, the USS Defiant entered this space when it was under the control of the changeling Krajensky. (DS9: "The Adversary")
This area's quadrant of origin is inferred based on the position of the Tzenketh system as seen in the star chart appearing in the Star Trek: Picard episode "Maps and Legends".