Moonbase (Attack of the Cybermen)

A Moonbase was established on the dark side of Earth's moon by time travelling CyberNeomorphs, using a stolen timeship from Hatre Sedtry, in 1985. (TV: Attack of the Cybermen, PROSE: Attack of the Cybermen, AUDIO: The Ultimate Cybermen)

History
Earlier in the 20th century, the Cybermen of the "Early CyberFaction" from Planet 14 had established a base on the dark side of the Moon. (TV: The Invasion, AUDIO: The Ultimate Cybermen)

After the destruction of the time vessel and future Cyber-Control on Telos, some surviving Neomorphs were left stranded in the 20th century, remaining in their Cyber-base on the Moon, becoming CyberIsomorphs. In the CyberHive, ArcHivist Hegelia suggested that the CyberIsomorphs made contact and exchanged data with the earlier CyberFaction. The Faction remnant were influenced to retreat imto the mineral rich asteroid belt, regroup and building a stronger base from which to act. As a result, the Isomorphs had influenced the development of the Cybermen into what eventually became the Neomorphs. (TV: Attack of the Cybermen, AUDIO: The Ultimate Cybermen) The Isomorphs themselves were believed by Hegelia to have been destroyed in 1988, when the Seventh Doctor used the Nemesis to destroy their fleet. (TV: Silver Nemesis, AUDIO: The Ultimate Cybermen)