The Entity's dimension

From Tardis Wiki, the free Doctor Who reference
A portal to the Entity's dimension. (WC: Day of Reckoning)

The Entity, that entered the N-Space looking for the Emperor of the Restoration, (WC: The Archive of Islos) originated from another dimension, named by the Dalek Prime Strategist as The Entity's dimension. (WC: Day of Reckoning)

When the Daleks came for the Archive of Islos, the Archivians opened the portal to the Entity's dimension, allowing the population of the planet to escape the Daleks along with the contents of the archive. In return the Entity asked for the Dalek Emperor. (WC: The Archive of Islos)

During the battle of Mechanus the Entity was sent back to its own dimension by the Prime Strategist and Mechanoid 2150 who repurposed the orbital defence grid of Mechanus into a beam projector. (WC: The Deadly Ally)

After the Mechonoids started the Mechanoid-Dalek battle on Skaro, the Mechanoid Queen and 2150 attempted to convince the Strategist that he was not being given enough credit from the Emperor for his plan and that he should rule. The Strategist and Mechanoid 2150 planned to use a beam projector to open a portal to the Entity's dimension to send the Emperor through. However, to the horror of 2150, the Strategist instead used the portal to remove the Mechanoid army from Skaro and then closed the portal. (WC: Day of Reckoning)