The Jenkata Nebula was an interstellar gas cloud in the Gamma Quadrant, located near the Teplan system and the Obatta Cluster. In 2372, Major Kira Nerys took her runabout into the Jenkata Nebula to avoid detection by a Jem'Hadar patrol. (DS9: "The Quickening")
According to the Star Trek: Star Charts (pg. 75), the Jenkata Nebula was located in or near Dominion space, in the Gamma Quadrant.