The Gnarled Wall

Created by druids at the end of the Great Borean War, the Gnarled Wall is the main dividing construction between Phesunlay and the Bandit Lands. As the creation of the Bandit Lands was a core tenant of Hession's Peace (though one that Hession himself did not agree with), the creation of the Gnarled Wall was a crucial project to ensure that dangerous war criminals condemned by the Kentasorte could not return to general society.
The Gnarled Wall spans from the southern coast of Hag's Bay in the north, and a northern inlet of the Strait of Aloc in the south. The Gnarled Wall was created with powerful druidic magic, requiring many druid working in unison to spawn and grow a variety of trees and vines which could interweave into a twenty meter high living wall. Many of the plants in the Gnarled Wall are easily recognizable, though contorted to unnatural sizes. Branches and boughs from the Gnarled Wall extend into the Bandit Lands, and roots from all the plants drive deep into the ground.
At a point near the centre of the wall's span, there is a giant oak tree which serves as a door to the Bandit Lands, known as the Oak Gate. 
The Gnarled Wall is constantly maintained by a host of powerful druids known as Wallshapers. The Wallshapers are trained like many other druids, but they go on to live on the Gnarled Wall and maintain it for most of their lives. The outer surface of Gnarled Wall, on the side of Phesunlay, contains a myriad of homes and huts and other structures created directly onto and with the Gnarled Wall itself by the Wallshapers. Some of these houses are at ground level (especially homes for druids with families), but many more are perched part way up the wall and require druidic abilities to even reach. Some of the homes are moved, from time to time, as is seen fit by their owners. At all times, there are several houses or roosts built onto the top of the wall, to allow some Wallshapers to keep watch every day and adjust the wall as needed to prevent any escape attempts.
The Gnarled Wall itself is a living wall, meaning all of the plants that make it are still alive, tended to by the Wallshapers. While the true thickness of the wall varies from place to place, it is always at least 10 metres thick. The Wallshapers who maintain the wall not only keep it growing and prevent any of the plants from succumbing to disease or fire, but they also maintain the magical properties of some of the plants that make up with the wall which help it resist all damage.