Shadow Dimensions

The Shadow Dimensions (TV:, 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: ) Torchwood's Captain Jack Harkeness 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: )

While "the Entity" considered the dimension to be his domain, the Mandarin contrarily felt it was rather his prison. (PROSE: )

History
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: ) 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 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: )

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: )