Alfheim is the racial homeworld of the Star Elves and it is a moon of a gas giant planet, the same gas giant around which Asguardia, the racial homeworld of the Asguardian Dwarfs, orbits. 

Alfheim is also the intergalactic capital of the United Planets, and the Star Imperium before it. 

Until 340 years before Year 1, Alfheim was politically divided into hundreds of nations and city-states governed by hereditary rulers bearing the title of Archon. Then the moon of Alfheim was united under a monarch, the Imperial Sovereign, with the old nations and city-states abolished, though the former Archon rulers gained hereditary seats in a Council of Archons that advised the ruling sovereign.

After the formation of the Imperium in Year 1 until the establishment of the United Planets in year 13,100, the ruling Imperial Sovereign (or the Council of Twelve in cases the Sovereign was incapable of fulfilling his or her duties or the office was vacant) was responsible for the local government of Alfheim. After the establishment of the United Planets, what remained of the Imperial Parliament provided for the local governing of the moon.