Corellia is a planet within the Pocket Universe whose population is mostly Humans. For thousands of years, new humans have arrived on Corellia from Earth in the Old Universe via the Wormholes. The planet originally was governed by an absolute hereditary monarchy, although by Year 2350 in the Shi'ar Calendar the ruling monarch's power was limited by a democratically elected Corellian Council.
When it comes to political affiliation on an interplanetary or interstellar level, Corellia originally was part of the New Shi'ar Imperium by Year 3000, but broke away from the Imperium during the Era of Anti-Imperial Rebellions to become a founding member of the Systems Commonwealth in Year 6904.
In recent centuries and millennia, the planet has shifted between being part of the Commonwealth and being conquered by the Sontaran Dominion no less than 20 times. Even under the rule of the Sontarans, Corellia has retained it's traditional monarchy and elected Corellian Council, although the Sontaran Emperor has generally appointed a Sontaran or a pro-Sontaran human as planetary governor with veto power over the decisions and policies of he local regime.