Timeline

Here is a timeline of the world - this is much more detailed than would be known to the average citizen of Lighthold. This is as much information as most scholars or mid-level clerics or wizards would be able to give you. It is not 'common knowledge', knowledge accessible to those who took steps to find out.

Only the most venerable archmages and the gods themselves know more, and even then, barely any certain fact remains even of the third age, let alone before.

The majority of information before the fourth age is passed on by contradictory legends, and confused by contemporary storytellers who insist on adding their own twists and fabrications.

Immortals
Convention has it that the first beings were gods or titans, beings initially of thought and magic, slowly descending through the aeons to physical forms like their creations. Some legends tell of four groups of god-beings: Gods, Fiends, Titans and Primordials. Others list Archfey, Star-Beings, Inscrutables, Inevitables, or others.

Mortals
It is usually argued that mortal creatures have existed since before the first age at least, although there is no hard evidence until the third age (!). Some storytellers place their race as the first among equals, who or what came first and who they were made by is unknown. 

Coexistence
The various races of god-beings (and possibly their creations) lived and built in peace, for a time...

The sundering
No-one knows why, but at some point, the different god-beings warred on each other. Some legends place the war at a decade, others a century, others ten thousand years. However long it was, this is usually referred to as the first age. The various war myths conflict, but the gods and their rivals (whether titan, primordial, fiend or whatever) ground each other down until the gods finally killed or imprisoned the others. The only facts certain is that there was a huge war which resulted in a godly victory. The most powerful gods gorged on the spoils of their crushed enemies - Divine Essence - and ascended beyond physical form.

Pax
A great spell of peace was woven by the greatest deities on their ascension to Overdeities. For a time the remaining gods ruled together, but eventually began to compete rather than coexist, demand worship rather than simply guide. Each developed a taste for power and excess. Conflict was inevitable. A younger god (named provocatively in some modern retellings as Kursus), evil, ruthless and greedy, tricked the other gods into breaking the pax and attempted to acquire sole godhood of the cosmos.

Campaign
(I have a 'high-magic' campaign which runs in this era of the world.)

A divided pantheon
A great war between the gods shattered civilisation and fractured the multiverse. A small group of mortals (names lost to history) rose to godhood from the ashes and taught the survivng gods humility. Together they helped rebuild civilisation.

A mortal pantheon
The new gods knew too well the devastation of an inter-pantheon war and vowed never to accumulate power and weapons, never to fight. They did not hoard divine essence and build up divine powers as their predecessors had done. They remained weaker, more peaceful, and guided civilisation to the same end.

The primordial war
Unfortunately, the essence pool godhood, flowing through the multiverse and unused by the weak gods of peace, seeped into the world itself. As the gods tried to reshape the world, the world took life and form and power and rose up to destroy them. The elements themselves became primordial gods and there was yet another war. The formerly mortal gods won, though barely, and one by one decided to pass on from the world, surrendering their divinity and dying as mortals.

During and after the war, the Gods Passed created new, more warlike gods, from scratch. The first of these was Alastor. Some stories say that Irar and either Malos or Kursus were made as his brothers immediately. Others say all twelve of the Throned Ones were made during the war. The gods of the third age also found, created, or promoted other gods no longer existing today (usually having fallen in the war), notably the Huntress Past.

A designed pantheon
The pantheon passed did not leave civilisation unprotected. The primordials could rise again. To prevent divine essence flowing freely and awakening other forces, the gods of the third age designed and created the pantheon known today. Once the patheon passed left the world, the Throned Ones became the new and only pantheon.

Cradle of light
TBA

Current Events
Afelhas

The present day is 2131 IV