in the Milky Way, including Earth, from Goa'uld attack. They also provide much assistance to Earth in the way of technology, equipment, and expertise. Their main adversary in Stargate SG-1 are the mechanical Replicators, against which they enlist the aid of SG-1 on several occasions. The entire Asgard civilization chooses to self-destruct in "Unending", due to the degenerative effects of repeated cloning. A small rogue colony of Asgard, known as the Vanir, still exist in the Pegasus galaxy. They were able to slow cloning's negative side effects by experimenting on humans. Mythology of Stargate SG-1 Stargate SG-1 takes place mostly in the Milky Way galaxy. Brad Wright and Jonathan Glassner tried to stay true to the feature film, but also wanted Stargate SG-1 to be unique in its own way. Stargate SG-1 gradually evolved away from the basic premise of the film and developed its own unique mythological superstructure. Stargate SG-1 elaborated on the film's Egyptian hybrid mythology and mixed in other historical mythologies, coming up with a mythological superstructure that explains the existence of all of the other mythologies in the overarching Stargate narrative. The series expands upon Egyptian mythology (notably the Egyptian gods Apep/Apophis, and Anubis as Goa'uld villains), Norse mythology (notably the god Thor as an Asgard ally), Arthurian legend (notably Merlin as an Ancient ally), and many other mythologies like Greek and Roman mythology. SG-1 does not introduce new alien races as often as some other science fiction television series. Most civilizations that the Goa'uld had transplanted maintain much of their original Earth culture, and Stargate SG-1 does not equate civilization with technology like many other sci-fi shows do. Newly encountered races or visited planets are integrated into the mythology, although plotlines of individual episodes are often new, self-standing and accessible for new audiences, giving a compelling internal coherence. The writers had to strike a balance in the interaction between the explorers from Earth and advanced races (of which there were only few in the story) so that alliances could be developed where the advanced races do not give Earth all their technology and knowledge. Stargate SG-1 emphasized its present-day-Earth story frame by frequently referencing popular culture, like The X-Files and Buffy the Vampire Slayer had done before. According to one critic in 1997, Stargate SG-1 was designed to have no nationality, which might appeal to viewers all over the world. The final episodes of season