Situated along the valley of the River Tesh, Teshendale was a lost dale once occupied the territory spanning from Zhentil Keep to the Desertsmouth Mountains. Now, the area is covered in ruins, as in 1316 DR it was invaded by Zhent forces and orcs working for them; the people was slain, ensalved or driven away, the valley was quarried and the granite used to build vast sections of the walls that protect Zhentil Keep.
Although no longer part of the Dalelands, the cities of Teshwave and Snowmantle remained under control of Zhentil Keep until its destruction; Teshwave, once the largest trading community in Teshendale, was a staging area for Zhent nonhuman troups and mercenaries. Snowmantle, located along the edge of the Border Forest, was a Zhent logging camp.
The Dales Council continues to keep an empty seat for Teshendale as a reminder of what happens when the Dales do not stick together.