Deep Periphery refers to the depths of unexplored space and/or human colonized space located beyond the (known) coherent human sphere of influence, namely the Inner Sphere and the adjacent Periphery realms. Due to the vague nature of the term "Deep Periphery", there is no clearly defined beginning nor are there any boundaries.
Though largely uncharted, the Deep Periphery is far from uninhabited. The Deep Periphery is littered with abandoned or failed colonies, small outposts, and even interstellar empires. Many periphery and Inner Sphere factions also maintain hidden bases in the Deep Periphery. The Clans have established numerous garrisons, depots and cargo waystations between the Clan Homeworlds in the coreward periphery and the Inner Sphere, sometimes by occupying an already inhabited system.
Excepting Clan space, no established HPG communication network exists within the Deep Periphery; communication is only possible via courier ship. While this is also true for the greater part of the near periphery, the distances involved mean that many Deep Periphery settlements are isolated from the rest of humanity.
Below is an incomplete list of Deep Periphery realms and settlements:
- The Hanseatic League
- The Chainelane Isles
- The Castilian cluster
- The Khwarazm Empire
- The JàrnFòlk
- The Society of St. Andreas
- The Union of Samoyedic Colonies
- The Axumite Providence
 Independents and Colonies
 The Clans
Though the Clans may be considered distinct from most Deep Periphery denizens, a list of settlements are provided: