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- You may be looking for Section 31, the rogue Federation agency.
Sector 31 was a region of Federation controlled space near the Romulan Neutral Zone.
In 2364, communication with Starbases in this sector, and outposts in neighboring Sector 30 ceased as of stardate 41903.2. The identity of the assailant that had destroyed the bases was unknown at the time. (TNG: "The Neutral Zone") It was later on determined that the Borg were responsible for the attack. (TNG: "Q Who")
In 2259, in the alternate reality, sector 31 was located in or near space occupied by the Klingon Empire. The location of the sector was depicted on a star chart displayed in the office of Admiral Christopher Pike and the office of Admiral Alexander Marcus. (Star Trek Into Darkness, display graphic [1])
According to Star Trek: Star Charts (p. 66), Sector 31 (Glintara Sector) was located in the Beta Quadrant. The sector was named after the star Glintara.
The lower corner of the star chart in Star Trek Into Darkness was labeled as the Alpha Quadrant, suggesting this sector was located in there instead.