This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
The Mutara sector was a region of space under Federation control. The Genesis sector, an area of space within this sector, consisted of the planet Genesis that was created when the Genesis Device exploded inside the Mutara Nebula.
In 2285, Khan Noonien Singh, aboard the hijacked USS Reliant detonated the Genesis Device within the Mutara Nebula, creating the Genesis planet. As a result of the incident, travel in and out of the sector was restricted by Starfleet. Additional permits were required, making commercial and non-military travel more difficult and more expensive. (Star Trek II: The Wrath of Khan; Star Trek III: The Search for Spock)