The Path of Black Leaves

The Path of Black Leaves is the domain of the Slender Man and is commonly used by the Slender Man's proxies as a mode of travel. It has been described as "Dead quiet street. No one in sight. The trees on the sidewalk are filled with Black Leaves." It also has a forest. Creatures are said to roam the forest and attack those who do not bear the Slender Man's Mark. Loops and Labyrinths might be extensions of the Path of Black Leaves created by Slender Man to trap it's victims. The Path is also where the Bleeding Tree is located.

Pavelverse
In the Pavel Hall universe the Path is not quiet. There is always screaming, presumably by the Creatures attacking people.