Frigus

Frigus is an arctic planet stuck in permanent winter. Though the planet lies in Imperial space, the planet and population is not governed by the Imperium, but is considered a vassal. The population of Frigus does not have a central government, but is instead ruled by scattered tribes.

History
The first settlers of Frigus were originally the crew of privates crash landing on the planet after trying to avoid foreign authorities not belonging to the Imperium. The crew of the ship were forced to settle on the planet due to their ship being completed ruined and no one coming to save them. After several centuries, the small crew of pirates grew into several tribes and had evolved to withstand the harsh cold and had even created their own religions.

When the Imperium had annexed the star system that Frigus was in, they sent a group of colonists to colonize the planet after thinking that no one was living on it. The colonists were ambushed by a tribe and were forced to flee the planet. The Imperium later arrived with a large military force and quickly conquered all tribes with their overwhelming might. But they were shocked to realise that the native population still resisted and could not be ruled by traditional means.The Imperial government then decided that it would be better if they vassalised the planet instead of ruling it by force, letting the natives rule themselves as long as they pay tribute.