On the Forgotten Realm’s Wiki, Anauroch is described as the result of phaerimm casting lifedrain spells which transformed the fertile lands of Netheril into the desert that it is today.
But there is also an inconsistency as the SCAG lists Anauroch as still existing whereas the Forgotten Realm’s Wiki lists that Anauroch no longer exists as a desert and is just a dust bowl.
Additionally, across 5e SCAG, PHB, DMG, and the MM, there is no reference of phaerimm creating the desert of Anauroch.
Here are the relevant quotes:
In -461 DR, the phaerimm started casting spells in the land of
Netheril. [6] These spells were the magical cause of
Anauroch.[citation needed]In 10 DR, the Netheril region was renamed Anauroch,[7] to reflect the
great desert that the region had become.[citation needed]The arrival of Thultanthar in 1372 DR[8] heralded the beginning of the
end of Anauroch.[citation needed]By 1479 DR, the end of Anauroch was complete and only occasional
dustbowls remained as a reminder of the once great desert.[9].
For 5e, how are these discrepancies resolved and what is canon for the creation and current existence of Anauroch? Additionally, is there any clarification of what is canon for the 5e universe versus the fiction that is written or past edition DnD books?
Best Answer
What is the canon for the creation of Anauroch?
According to Netheril: Empire of Magic boxed set (TSR 1147, published in 1995), what is currently the desert Anauroch used to be lush lands 5000 years ago. Those were the lands where seven fishing villages first formed a kingdom (-3859 DR), named after the king Nether the Elder (and his successor, Nether the Younger).
In time, the kingdom discovered the so-called nether scrolls, which allowed its citizens to master magic quickly. Within the ninth century of the foundation of the Netherese kingdom, they had already managed to create the first floating cities. They kept on expanding and started wielding immense power.
Into their fourth millennia, an outcast named Olostin came across a strange cone-like being, a member of the race phaerimm. After information gained from Olostin, the phaerimm starting casting "magic drain" spells in the year 3398 (-461 DR). These had devastating effects:
Some three centuries after the fall of the empire, which was caused by the attempt of one overambitious archwizard, Karsus, to become a god, the spread of the desert had stopped. It is not clear why, but it is possible that the sharn, a race of beings who are enemies of the phaerimm, might have played a role. (This is confirmed in the sourcebook Lost Empires of Faerun, published in 2005.)
What is the canon for the disappearance of Anauroch?
According the Forgotten Realms Campaign Setting (published in 2001), the City of Shade, one floating Netherese city that had disappeared into the plane of shadows right before Karsus's folly, reappeared over the skies of Faerun in 1372 DR.
We learn from the Forgotten Realms Campaign Guide (published in 2008), within a century of their return, the Netherese had struck hard on the phaerimm, and the desert was reclaimed:
It appears this is the current (Feb 18, 2018) status of the Anauroch entry at the FR wikia.
What is the canon for the recreation of Anauroch?
Finally in 1487 DR, the City of Shade falls on top of Myth Drannor; as we read in the Sword Coast Adventurer's Guide (published in 2015, page 18). This causes the destruction of both cities. A year after, a battle in the Netherese lands awakens a hive of phaerimm, and they use life and magic-draining power of the so-called Memory Spire causing the desert to come back.
While the first desertification of Anauroch was a very long process taking centuries, the second time it seems to have happened in a manner of years. But it has indeed become a desert, as mentioned multiple times in the SCAG:
Conclusion
There are no conflicts between the past official material and the information provided in the SCAG. It is just that the creation of the desert has happened twice.