Waterdeep - Melairbode (–1288 to 211 DR)
Even before the Fair Folk abandoned Aelinthaldaar, a shield dwarf named Melair discovered a vein of precious mithral beneath Mount Waterdeep in –1288 DR.
King Melair I, as he came to be known, sent word to his kindred, and those who answered his call became Clan Melairkyn. The Melairkyn were traders, artisans, and explorers, strongly protective of their home, which they named the Underhalls of Melairbode.
They slew or drove off Underdark predators, duergar miners, and drow scouts in order to establish their realm.
As the Melairkyn extended the boundaries of their realm to include the topmost levels of what is now Undermountain, the leaders of Aelinthaldaar grew increasingly concerned.
Eventually a deal was struck, in which the Melairkyn would provide a great amount of mithral ore to the elves. In exchange, the elves crafted a high magic effect that would prevent the plateau from ever collapsing or settling, no matter what occurred in the tunnels below.
The plateau of Waterdeep still stands firm today, despite countless collapses in the caverns of Melairbode in the intervening centuries.