Limbo

Limbo is a realm that exists outside of time.

History
Limb is a place that was introduced in season 7 for the first time. During their last battle against the Trix, Bloom comes up with the idea to lock them in Limbo. By her then stated "outside of time".

They use the Stones of Memories to open the portal to Limbo. When the portal opens, the realm itself acts consciously as it immediately starts capturing the Trix.