Timeline

Post Transcriptum (Beyond 0)

↑ Year	Event
488	A bard sings the tale of Four Feathers.
444	Session 1 begins; Four Feathers forms.
430	Nexus Session 1 begins.
424	Abador citizens endure mass petrification.
357	Discovery of the Realms.
257	The Mor'kiin disease is discovered.
29	Founding of the Scarlet Academy.
??	Arcanum is discovered by Elrune Leonelis.
↑ Age of Discovery
0	The 100-Year War concludes victoriously.

Ante Transcriptum (Before 0)

↓ Year	Event
100	100-Year War commences.
↓ Age of Wilderness
~400	Brassdorf is formed.
~2200	Istros Borealis is discovered.
????	Myrneas is destroyed by Ozma.
????	Elves splinter and most migrate to Esuna.
????	Ozma is crowned king. Descends into madness.
Unknown	A great asteroid hits in Istros Borealis, creating World Eater. The world drastically changes.
↓ Age of Enlightenment
Unknown	A single large continent existed on Yggdrasil, a highly advanced civilisation was built here.

This is the complete timeline for Yggdrasil!

Age of Discovery

Directly following the 100-Year War, the largest ruling entities agreed to properly regulate the usage of magics. Powerful arch-mages around the civilised world banded together to catalogue and keep track of the various powers at large, forming the Scarlet Academy decades later to safely keep this information. Various other locations would also keep information and many governments would put forth laws regarding types of magics that were allowed to be used. While this is largely a collaborative effort to keep it regulated, not all types of magics were seen equal. Some parts of the world might consider Necromancy a forbidden magic, but others may consider some or all of that type be useful.

Elven knowledge

The Sylvan Realm has by far the largest knowledge base in the world. The long lifetime of the elven race allow them to better record or even witness notable historical events. That recorded knowledge is kept in their large cities, most notably Yls Dorei or in one of their many knowledge banks such as those in Aerthys. Sylvan Realm record-keepers remain vigilant protecting the many assorted libraries with vast knowledge, access to them is strictly forbidden and, for many non-Elven creatures, even punishable by law. Though a portion of records may be accessible what is deemed low importance to their citizens, access remains limited nonetheless.

Age of Wilderness

The history before the 100-Year War remains largely uncertain as relics scattered throughout the world in hidden ruins or texts long forgotten in old libraries, abandoned or otherwise forgotten. The world populace was not as interconnected as today, information did not travel far as means of migration did not expand yet during this time. In addition to the lack of some centralized bookkeeping, many scriptures and other records from this era would use different forms of dating systems making it difficult for modern researchers to reconstruct the sequence of events as a coherent flow of that time. As a result, many facts of this era are still studied and kept in storage in the hopes that a technology will someday exist to properly sort them in chronological order.

What is known is the scattered tribes and factions that lived throughout this age. Little is found in connection with the deities though the use of magic is found in virtually every developing culture. Most tribes worshipped the users of magic as its effect were majestic and powerful, many of which such users ending up as leading figures and were often seen as descendants of the forgotten gods.

Age of Enlightenment

By the words of Alenriel, a time-displaced elven paladin who appeared 444 PT, the world consisted of only a single large continent on which a highly advanced civilization existed. The people of this time had direct contact with the deities of the ulterior planes and even magic itself had a different flavor and flair.

This continent would ultimately be destroyed by a catastrophic asteroid impact on the northern region of the old world. The continent would subsequently split to create Esuna, Avalon and the Eastern Kingdoms with the remaining chunk left to become Istros Borealis on which now the World Eater crater is left with its surrounding highly irradiated ice keeping curious eyes at bay.