The peaceful world of Cimmeria falls under the Asgard's Protected Planets Treaty with the Goa'uld System Lords. The people are a primitive, pre-industrial Viking society. Strong in their Norse beliefs, they are taught from birth that Thor is their protector. This was well maintained until the Tau'ri contaminated the Asgard's timetable for the natural progression of Cimmerian society.
For centuries the Cimmerians had little understanding of the true natures of the "gods," believing that Thor was an enormous warrior. But after SG-1 destroyed Thor's Hammer, a piece of Asgard technology left to protect them from the Goa'uld, Heru'ur arrived and enslaved the population. Gairwyn, one of the Cimmerians leaders, was taken aboard Thor's mothership Beliskner and learned the truth for herself -- though she was not swayed in her beliefs that Thor was her people's protector ... despite the fact that he is a little grey alien.
A new Hammer device has since been placed on the planet, and the Cimmerians are once again defended, allowed to proceed in their natural understanding of the world around them until they are, one day, prepared to join the greater community of the galaxy.
Thor's Hammer - SG-1 meets the Cimmerians, who follow Norse mythology and worship Thor. But they are forced to destroy the Asgard technology that protects the planet, leaving them vulnerable.
Thor's Chariot - The Goa'uld Heru'ur invades Cimmeria, and SG-1 must overcome the local people's distrust of them to defend their world and get help from the Asgard.