Anti-zone

From Tardis Wiki, the free Doctor Who reference

According to the Thirteenth Doctor, an anti-zone was "a thing the universe [made] wherever the fabric of space/time [was] threatened", acting as a protective buffer zone.

She entered one such anti-zone through a portal located in a mirror on Norway. That anti-zone separated the Doctor's universe from the Solitract plane. (TV: It Takes You Away)