Regalis Sector
From Tardis Wiki, the free Doctor Who reference
The Regalis Sector was a location once visited by the Thirteenth Doctor. The area was considered "hotly contested" by the Sontaran Empire, but gave them unconfirmed reports of the Doctor's new form. The Sontaran Subliminal Education Matrix mentioned these reports to Strax shortly after his creation. (PROSE: A Soldier's Education)