- You may be looking for the dimension lived in by another Entity, known as the Slave of the Hond.
The Shadow Dimensions (TV: The Curse of Fenric [+]Ian Briggs, Doctor Who season 26 (BBC1, 1989)., etc.) was a bleak grey void with shifting patterns which formed the surrounding. According to the Mandarin, the dimension was an "unimaginative" non-world, a "dimension of shadows and half-lives". (PROSE: Games [+]Warwick Gray, Brief Encounters (Marvel Comics UK, 1992). Page 22.) Torchwood's Captain Jack Harkness also described the dimension as being devoid of anything but the sorrow and guilt of the lost and the breeding ground of creatures that drain emotional energy. (AUDIO: The Sin Eaters [+]Brian Minchin, BBC Torchwood Audiobook (BBC Audio, 2009).)
While "the Entity" considered the dimension to be his domain, the Mandarin contrarily felt it was rather his prison. (PROSE: Games [+]Warwick Gray, Brief Encounters (Marvel Comics UK, 1992). Page 22.)
History[]
Information from AUDIO: The Sin Eaters and Fenric's escape from the Shadow Dimensions in TV: The Curse of Fenric should be added.
The Doctor banished Fenric to the Shadows Dimensions in a flask during their battle in the 3rd century at the conclusion of a chess game. (TV: The Curse of Fenric [+]Ian Briggs, Doctor Who season 26 (BBC1, 1989).) According to the ancient Arabian legend of their encounter, the flask contained the "Seven Shadows". Like Fenric himself, the Shadows were a remnant of "the time before Time". (PROSE: The Curse of Fenric [+]Ian Briggs, adapted from The Curse of Fenric (Ian Briggs), Target novelisations (Target Books, 1990).)
The Mandarin was unimpeded in reaching the location, having wanted to challenge "the Entity" before his banishment. There, the Mandarin and the Entity played a game of four dimensional chess, eventually reaching a stalemate. The Mandarin thanked the Entity for teaching him that concept, fading away as he left; the words spoken by the Mandarin remained with the Entity long after he left. (PROSE: Games [+]Warwick Gray, Brief Encounters (Marvel Comics UK, 1992). Page 22.)
Undated events[]
The Demon described his home as being "a tiny backwater in a shadow dimension... bearing practically no resemblance to this physical universe." While the Shadow Dimensions were inside the flask, they may also have existed outside the universe, where the Demon was from. (AUDIO: Sepulchre [+]Paul Magrs, Demon Quest (AudioGO, 2010).)