Ascalhorn was founded by the Eaerlanni elves in the northeast of the High Forest on an area known as Ascal’s Horn, to protect the boundaries of the kingdom. They gave it to the Netherese refugees after Netheril fell.
Wulgreth, a Netherese wizard, summoned devils to the city in 820 DR. In 880 DR, this prompted other wizards, with the guidance of the fey’ri, to summon demons to counteract the devils and in 882 DR the demons won the battle and subsequently conquered the city. The demons continued their rampage, destroying Eaerlann and Ammarindar.
In 886 DR, Harpers placed wards around the keep to prevent demons from using their gate abilities.