The Forest of Bierteno was a large forest in eastern Aels, located east from the Barlans and to the west of the Nohalion mountains, being often seen as a unity with the forest of Nubla. The Forest of Nubla being on the east side of the Nohalion Mountains, and running east to or nearly to the sea. The Forest of Bierteno running west from the Nohalion Mountains towards the Barlans.
But, again, Bierteno is often seen part of the greater Forest of Nubla as only the mountain range divides the foest. And the Nohalion range of mountains are broken into the North, Central, and Southern ranges. The interspersed areas the mountains shrink to low mountains or hills, or even fairly flat land, with forest running unbroken over these ridges.
The forest of Nubla, an old and dense forest, it was house to Loranor, Fairy, Draak Harg, Wollumis and Sylvan elf peoples among many others, being as well seen as magical, refuge of many of the Aelian myths.