InnerSphere

The Inner Sphere is the central region of human-inhabited space in the BattleTech universe. It is the homeland of the Successor States formed after the fall of the Star League and contains the major political realms known as the Great Houses. The term distinguishes it from the Periphery, a frontier zone, and from Clan Space, which is controlled by invading Clans.

Geography and society: It comprises hundreds of star systems organized into rival polities. Its core worlds host industrial and economic hubs that drive interstellar trade and military production. The Periphery surrounds and interacts with it through commerce and conflict, while Clan Space lies beyond the Inner Sphere's borders.

Politics and history: After the Star League collapsed, the successor states vied for power in a long series of dynastic conflicts known as the Succession Wars. The five Great Houses—holding the Federated Suns, Capellan Confederation, Draconis Combine, Lyran Alliance, and Free Worlds League—shaped political borders and alliance patterns. The era is marked by shifting coalitions, treaties, and often fragile truces, with occasional escalations that redraw the map.

Military and technology: The Inner Sphere maintains a heavy industrial base that drives the production of BattleMechs, aerospace craft, and battle fleets. Military doctrine evolves through periods of stalemate, reform, and external pressure, including incursions by external powers that periodically disrupt the balance of power.

Culture and demographics: The Inner Sphere is culturally diverse, with distinct traditions and governance practices tied to each House and system. Language, religion, and social norms vary widely, but political legitimacy, dynastic loyalty, and economic strength are common themes shaping daily life and statecraft.