The Taugan sector was a region of space. Many planets in this sector were home to ancient Romulan and Debrune, an off-shoot of the Romulans, settlements. Most of this sector was in Federation territory.
Six months prior to stardate 47135, in 2369, Arctus Baran and his band of mercernaries started raiding several planets in the search for ancient Vulcan artifacts. (TNG: "Gambit, Part I", "Gambit, Part II")