Inner Sphere

In the fictional BattleTech universe, the Inner Sphere is a region of interstellar space, ruled by the five Great Houses (each of which dominates one of the "Successor States".) After the fall of the Star League, the Inner Sphere fractured as each of these Houses attempted to secure rulership during the Succession Wars. The Inner Sphere is bounded by the Periphery; the relationship between these regions is analogous to that of the developed nations and the Third World. Beyond the Periphery is unexplored space, and the Clans.

New Avalon
Capital of the Federated Suns and later the Federated Commonwealth.

Luthien
Capital of the Draconis Combine.

Sian
Capital of the Capellan Confederation.

Atreus
Capital of the Free Worlds League.

Tharkad
Capital of the Lyran Commonwealth, later the Federated Commonwealth and, even later, the Lyran Alliance.

Solaris VII
Located in Lyran space, Solaris VII is also known as the gaming world.