The Tandar sector was a region of space controlled by the Tandarans.
Thousands of Suliban emigrated to this sector after their homeworld became uninhabitable in the 1850s, but when the Cabal began a war against the Tandarans in 2144, all of the Suliban were rounded up and placed in detention camps for fear that they would provide an avenue for infiltration by the Cabal. (ENT: "Detained")