Parallel dimension (Telepresence)

A parallel dimension was one of several universes invaded by the Cybermen of the Cyber-Mainframe during their mission to upgrade the entire multiverse. (AUDIO: Telepresence, Master of Worlds)

History
During the Last Great Time War, crashed his TARDIS in this universe while "exploring possibilities". Sometime after, the Cybermen of the Cyber-Mainframe broke into this dimension as part of their campaign to upgrade the entire multiverse. (AUDIO: Master of Worlds)

The Cybermen conquered this universe's Earth and enslaved the planet's human population as batteries to power the Cybermen in their multidimensional conquests. (AUDIO: Telepresence, Code Silver) Sometime after, the Petronella Osgood, Vikram Shindi and Josh Carter of N-Space used dimension bridge technology to access this parallel Earth in the form of mental avatars. After exploring the ruined Earth and evading the Machine's attempts to convert them, the trio accessed an underground train station in Piccadilly Circus, and eventually found a huge cavern in the tunnels that housed thousands of human batteries. The Machine then confronted Osgood, Shindi and Josh, before using Mechanising Worms to convert them and form a dimension bridge to N-Space. The Machine activated Hive Section 49, (AUDIO: Telepresence) a force of ten Cybermen, including a Cyber-Controller and a Cyber-Commander, (AUDIO: Code Silver) and sent them across the dimension bridge to N-Space. (AUDIO: Telepresence)

The Master was able to avoid being detected by the Cybermen and stole various components of Cyber-Technology to repair his TARDIS. Shortly after Hive Section 49 began invading the Earth of N-Space, the Master flew his TARDIS across the dimension bridge and back into his home dimension, and begrudgingly assisted Kate Stewart in stopping the Cybermen's conversion of N-Space. Shortly after, the Master left in his TARDIS to return to the Last Great Time War, and the dimension bridge connecting N-Space to this dimension shut down. (AUDIO: Master of Worlds)