The Great Sand Sea, was a magical desert in northern Faerûn. It held the remnants of the once-powerful Netherese Empire, their flying enclaves having crashed to the ground when their greatest mage Karsus, in a desperate bid to end the war against the phaerimm, challenged the goddess Mystryl for her divine mantle, causing the Weave to falter and all magic to fail. For generations since, Anauroch, the greatest desert in Faerûn, encroached relentlessly on border nations, burying them beneath the sands.[citation needed