The Obsidian Isles
The Vanguard are an advanced arcane civilization that lived nearly a millenia ago. Vanguard however is not their actual name, but rather a title given to them by those who came after as a tribute. According to historians, they referred to themselves as the Afaeriens (Ah-fay-re-in-s), though only those well versed in ancient history are likely think that. Most believe that Vanguard is their actual name.
Before The Fall, the Afaeriens built a civilization that spanned most of the known world. Their ruins still can be found littered across the world of Korin, but by now almost all of them have been looted, scattered, and lost to time.
Nearly all arcane understanding that the people of Korin have today is thanks to the
artifacts left behind by the Afaeriens after The Fall. Through years of study some have been able to reverse engineer their arcane relics, and piece together their secrets. This has brought upon a new age of arcane understanding, and progress.
The Afaeriens didn’t speak common, or at least, they didn’t write in common. All text recovered from Vanguard ruins seem to suggest that they spoke an ancient dialect of Elvish, though even native speakers of modern Elvish struggle to make out words and phrases. There are a few in the world who have learned it fluently, but most common folk will find it near impossible at best without some form of aid.