The Aldebaran sector was a region of space in the Beta Quadrant of the Milky Way galaxy. In the 23rd and 24th centuries, the majority of this sector was space claimed by the United Federation of Planets, though Klingon space did extend into the sector as well.
To the galactic west, on the opposite end from Klingon territory, the Aldebaran sector was bordered by the Betazed sector and the Betreka Nebula, while the Briar Patch was to the galactic northeast. (Star Trek: Star Charts)
The sector's name was derived from its most prominent star system, Aldebaran. The sector was one of the core regions of the UFP, and home to numerous Federation worlds and installations. Significant locations include the 14 Eridani and Eta Eridani star systems, and Starbase 133. (Star Trek: The Final Frontier, et. al)