How come that in the world of the Third Horizon, Al-Ardha is a long-lost memory?
There were several hundred thousand people from Terra in cryosleep on the Zenith.
Did they lose their memories during their thousand-year long slumber?
If not, they should have had relatively recent memories of Earth, the planet of their youth.
Some of those might even be around in the present day.
Also, there should be some written records left.. people had a lot of time to write down their stories after they woke up.
Just some food for thought.
Sorry about the late answer, but here it comes at last.
The Zenith and Nadir were both generation ships and cryo-sleep ships. About a hundred thousand souls embarked on each vessel aimed at he big red star, known as Dabaran in The Third Horizon (Aldebaran to us in reality).
The trip took aproximately 1 000 years. During that time the would be colonist were fast asleep in their cryo caskets using a now partly forgotten tech (not exactly the same as in stasis pods used for portal jumps). Tech that hadn’t been perfected and had some severe side effect. A lot of colonist died from the prolonged cry sleep, some went mad but almost all hade some sort of memory damage. During the wake up and strife between the Captain families (later becoming The Zenithian Hegemony) and the helmsmen families and other groups - a lot of colonist were lost and even more probably suffered memory damage of the speeded up wake-up process.
But what about the captain families, helmsmen families and all the other custodians of the ship. They were awake during the trip and most of them lived their whole lives during the voyage.
Rumor has it that some of the upper echelons of the Quassars (rulers of The Zenithian Hegemony) and The Draconites remember long lost Al-Ardha - but they keep the information to themselves.
Of course there are some zenithians who claim to remember Al-Ardha, but their stories diverge, from vast sunny deserts to magnificent cities with sky towers reaching to the skies. Most people don’t believe them as they often are stricken with some sort of lunacy.
Also, a lot of the people of The Third Horizon claim to be or call themselves zenithians, far more than the 100 000 or so to make the trip - that is just a cultural phenomenon - a way to describe yourself as modern and dissociate yourself from your Firstcome background.
Hope that answers your question