REDACTION (non-narrative. you couldn't be less narrative)
REDACTION is the name for an indeterminate period of time that was removed from causality. There are no records of any kind from these periods. All people who know about REDACTED were removed. Everyone they knew, every road they walked down, everything they touched or influenced in any way was completely erased at all layers of reality. At least one god was REDACTED and the gods that can be verified to have existed before and after REDACTION do not remember (or will not say) what happened during these times. After REDACTED there were large gaps in the bi-frost network where there simply were no disks, no asteroids, no stars, no moons, no nebulas, no matter of any kind was in the void here.
Redaction was not recognized until after the fact, it was not experienced as a sudden flash-forward but rather as a dawning realization that collective memory and history had massive unexplainable holes in it.
For humans this resulted in them not having a known home world with what would have been the core of their oldest states having been removed. This also largely destroyed their formal language, although it did not remove the language's importance in their culture, such that a restoration effort was undertaken to piece together whatever they could of it so that it could be spoken, such as it now is, in the modern era.
For Orks this resulted in significant changes. Prior to REDACTION they were in the middle of a deadly pandemic and another holy was was potentially brewing. After REDACTION the infection of the pandemic had apparently formed a symbiotic relationship with those infected who have formed their own culture, language, and governments independent of any orken governments during this gap in history.
The elves formed sometime during the time lost to REDACTION, forming from infected orks who were able to survive their infection until a strain of the fungus evolved which formed a symbiotic relationship with the infected host. Elves language and society was very thoroughly developed post-redaction indicating that a very large amount of their history was lost to REDACTION. Interestingly the amount of time lost to the elves appears to exceed the time lost to the orks.
Kobolds were largely unaffected, losing history but not undergoing any unusual changes during those lost periods.
Dragons were similarly unaltered and suffered little in the way of lost history or abnormal change. However due to their generally low population prior to REDACTION the reduction in population caused by the REDACTION of large numbers of individuals was especially noticeable. Dragons did seemingly attempt to create at least one new slave race during this period of time, though none will admit to any knowledge of such efforts. Post-redaction most dragons migrated into the realms of magic and the early dwarves were presumably left to fend for themselves.
For the dwarves this resulted in dwarves being a thing. Their culture, language, and multi-disk states appearing suddenly and fully formed. Whether or not their early history was REDACTED or not is difficult to ascertain as the religious and governmental organizations of the post-redaction dwarves have been highly unhelpful. Texts from that ear of dwarven history are both dense and archaic and without translation assistance outside scholars are unlikely to make any significant headway.