The Nether Scrolls

Long ago, an unknown adventurer discovered a set of magic writings that held vast secrets of magic. These writings came to be called the Nether Scrolls. Taken together, they granted insight into the mysteries of spellcasting, the creation of magic items and constructs, the relations and structure of the planes, and even the making of artifacts. Although all of the Nether Scrolls were lost or stolen over the following 2,000 years, by then the information they contained had changed Netherese society forever.

The lords of Netheril developed forms of magic never before seen in the world. The mythallar was a invention by the Netherese wizard Ioulaum that gave power to nearby items, negating the need for expenditure of a spellcaster's energy to create magic items. The mythallar also allowed the creation of flying cities, formed by slicing off and inverting the top of a mountain. Netheril's people took to the skies in these flying enclaves of magic, safe from human barbarians and hordes of evil humanoids. Every citizen wielded minor magic, and the Netherese traded with nearby elven and dwarven nations, expanding the reach of their empire greatly.