At some point in the distant past, lesser guardians aligned to Pious' Ancient invaded Ehn'gha and exterminated the locals. These inhabitants had knowledge of and possibly contact with one or more of the Ancients, likely contributing to their downfall. Their blood still flows through the streets when Edward visits, and appears to fill a moat leading to the entrance.
The necropolis is a guardian colony by the time Aaron Roivas learns of its existence beneath his family home. Maximillian Roivas discovers Ehn'gha after Aaron's death, and defeats a guardian at the entrance. He is placed in an insane asylum shortly after, and the task of purging the dead city falls to his descendent Edward. In 1952, Edward uses the city's own magick power against its current rulers by configuring large focusing towers to cast a large-scale Dispel spell; the shock-wave seems to wipe out most of the eldritch creatures there. Edward seals the entrance to Ehn'gha with a mechanism that will not open until the planetary re-alignment in the year 2000. A guardian manages to teleport into the Roivas mansion and kill Edward two weeks before this occurs, proving that they were able to replenish their numbers to some extent over the half-century.
When Edward's granddaughter, Alex, investigates his death on the night of the alignment, she learns that she too must use the city of Ehn'gha's power to her advantage. Alex uses the focusing towers to summon the Ancient that opposes Pious'. She is then teleported to an unknown location to do battle with the Liche, and finish him off. Edward appears one last time as specter to configure the towers to cast a Bind spell, preventing the Ancient Alex summons from remaining in this world. Ehn'gha's fate following this is unknown, but it is presumably free of the creatures infesting it, due to their Ancient's destruction.
- There is a minor in-game inconsistency with the way "Ehn'gha" is written. Text descriptions, such as Aaron Roivas' letters, use a lower case "g" (Ehn'gha), but when it is spoken in cut scenes it is shown in the subtitles with an upper-case "G" (Ehn'Gha).
- H.P. Lovecraft mentions an "N'gah-Kthun" in his story The Whisperer in Darkness. However, it is unclear if it's supposed to be a location or an entity.