An Eorzean Timeline.

[Catapult]

The fifth Astral Era did not begin until the discovery of magic brought society out of the ruins. This could be equated to a sense of hope being established amongst the entire population.

Eorzea doesn't seem to have that sense of hope in their recovery yet.

[Mtoto_Wamoto]

some updates to the timeline that are missing.

Fifth Umbral Era
The global ice age pushes man to the brink of survival.
Man discovers magic, bringing about the Fifth Astral Era.

Fifth Astral Era
Started some three thousand years ago.
Man begins to seek mightier magics thus the arcane art of destruction is born through Black Magic.
White Magic, the arcane art of succor, is created to balance the force of chaos brought with the creation of Black Magic.
Darkness descends upon man, causing men to pervert their new-found powers, bringing about the Sixth Umbral Era.

Sixth Umbral Era
Started some fifteeen hundred and odd years ago.
In order to purge the sins of avarice in man, the Twelve flood Eorzea.
A group of dark mages begin to wreck havoc upon the realm.
The Archons rise to battle the dark mages, yet one of the Archons, Ahldbhar, turns sides.
The Grand Companies are formed to ensure the realm survives, helping in bringing the Sixth Astral Era about.

Sixth Astral Era
0 - Start of the Sixth Astral Era (1572 years ago from 1.0 start, 1577 years ago from ARR start.)