The Hall of Mists, located deep inside the High Forest, was an ancient stronghold of the Ba'etith, an organization of sages and lorekeepers that began in the ancient sarrukh empire of Isstosseffifil.
In -2436 DR, an unknown thief stole seven of the Nether Scrolls, and three of them were hidden away in the Halls of Mists. The three Nether Scrolls were later scattered to other locations by Mintiper Moonsilver in 1344 DR.
In the Year of the Fell Firebreak, 883 DR, the magical chaos emanating from Hellgate Keep caused the place to be infested by giant red ants. The ants tunneled deep and opened passages to the Halls of Mists.