The Secret Garden
The Periphery is the part of the spirit world that is closest to the physical world, a place where spirit bleeds through into matter, perceptible to those with Awakened senses or merely a sufficient degree of Awareness. Umbrood and other spiritual elements can access the Periphery as a way to interact with the material world.
Beyond the Periphery lie the Schism, the Penumbra and the rest of the spirit world. The Periphery is the only part of the spirit world that can be accessed from the material world without having to brave the dangers of the Schism or making use of a Shallowing.
Creatures with a spiritual connection or heritage often spend time in the Periphery. The Periphery gives rise to any number of pockets of spiritually-influenced existence in the material world, including pockets of lost history, strange locations that seem incongruous with reality, lost glens, half-forgotten strongholds and the like.