Los Angeles, California, was one of the first human cities to fall. Nearly every single human being residing in it was slain by the local Horde King Lilith and raised into an undead. Nearly being the key word here.
Many of LA's survivors, which relative to their population prior to the outbreak of the Apocalypse, were miniscule in comparison had fled their homes and travelled north to a more… unsettled region of the infamous Golden State.
Here, a sanctuary for the living was established. Known by the name of "The Fields of Elysium" or Elysium for short. This rather substantial settlement was a self-sufficient community of survivors whose entire purpose in life was to help each other survive and thrive in this otherwise cruel wasteland. Over the months, Elysium had become known as a paradise within the wasteland, one where everyone's needs could easily be met by the governing body.