Taer-Sabál was once Taer-Dirion, the Tower of the Glade, built in TA 2271 by the rangers and druids of Arnor Forest. Taer-Dirion was a refuge for the rangers and a watch post for trouble in the forest. The tower was built in a large glade of the forest, called Afnuiël by the elves because of it’s star-like shape.
The tower was abandoned in TA 2543, during the declining years of the Calizan monarchy. Growing distrust between the Men and Elves forced fewer and fewer rangers and druids to patrol the forest. Although some remained, there were so few that the tower lost its value. Monsters of all kinds infested the tower year after year. Rangers and druids occasionally cleared it out, until even monsters eventually left it alone and so, then, did the guardians of the forest.
In TA 3186, the dwimmerslave, Jorlak Blain, occupied the tower and began restoring it. He renamed it Taer-Sabál, the Tower of Decay. In TA 3187, in addition to his already numerous Gor’Kresh troops, he obtained slaves from the Sindaeri to refortify the walls and rebuild the ruined parts of the tower.