History of the North - The Elven Exodus:

This era left behind elven strongholds ripe for pillaging by humans and orcs. When elves chose to leave the North and travel to Evermeet, their works quickly disappeared, leaving only places like the Old Road and a ruined port in the High Forest to mark Eaerlann's passing. And yet it was not only the elves who would disappear from their long-held homes; the human nation of Netheril also stood on the brink of history.

Doom for Netheril came in the form of a desert, devouring the Narrow Sea and spreading to fill its banks with dry dust and blowing sand. Legend states when the great wizards of Netheril realized their land was lost, they abandoned it and their countrymen, fleeing to all corners of the world and taking the secrets of wizardry with them. More likely, this was a slow migration that began 3,000 years ago and reached its conclusion 1,500 years later.

Whatever the truth, wizards no longer dwelled in Netheril. To the north, the once-majestic dwarven stronghold of Delzoun fell upon hard days. Then the orcs struck. Orcs have always been foes in the North, surging out of their holes every few tens of generations when their normal haunts can no longer support their burgeoning numbers. This time they charged out of their caverns in the Spine of the World, poured out of abandoned mines in the Graypeaks, screamed out of lost dwarfholds in the Ice Mountains, raged forth from crypt complexes in the Nether Mountains, and stormed upward from the bowels of the High Moon Mountains. Never before or since has there been such an outpouring of orcs. Delzoun crumbled before this onslaught and was driven in on itself. Netheril, without its wizards, was wiped from the face of history. The Eaerlann elves alone withstood the onslaught, and with the aid of the treants of Turlang and other unnamed allies, were able to stave off the final days of their land for yet a few centuries more.

In the east, Eaerlann built the fortress of Ascalhorn and turned it over to refugees from Netheril as Netherese followers built the town of Karse in the High Forest. The fleeing Netherese founded Llorkh and Loudwater. Others wandered the mountains, hills, and moors north and west of the High Forest, becoming ancestors of the Uthgardt and founders of Silverymoon, Everlund, and Sundabar.