As explained in the series' backstory, the Goa'uld had transported human slaves from Earth to other habitable planets across the galaxy thousands of years ago and now pose as gods of old Earth mythologies, particularly Ancient Egypt. SG-1 eventually learns that highly evolved human-like beings, known as the Ancients, had originally built the Stargate network millions of years earlier, before ascending to a higher plane of existence, after which they pledged not to interfere in the lives of other species. The Ori, a faction of the same race as the Ancients who instead use their powers to subjugate other species by religious indoctrination, assume the role of the main antagonists in Season 9 and Season 10. Goa'uld Arc The pilot episode ("Children of the Gods"), set one year after the events of the original feature film, introduces the Goa'uld System Lord Apophis (Peter Williams) as the main villain when he attacks Earth's mothballed SGC military base through the Stargate and kidnaps an airman. The SGC is brought back into action when the Stargate is revealed to be part of an interplanetary network connecting countless planets. SG teams are created to help defend Earth against the Goa'uld, who have interstellar pyramid warships and vast armies of Jaffa (hereditary slaves and human incubators to the Goa'uld) at their disposal. Earth's flagship team SG-1, which includes Apophis's defected First Prime (lead Jaffa soldier) Teal'c, initiates several alliances with other cultures in the galaxy, such as the Goa'uld-like but truly symbiotic Tok'ra, the advanced human Tollan, the pacifist Nox, the benevolent Roswell-alien Asgard and remnants of the powerful Ancients. Another alien threat arises in the Season 3 finale ("Nemesis") in the form of sentient machines called Replicators. Meanwhile, rogue agents of a shadowy intelligence agency on Earth, the NID, repeatedly attempt to take control of the Stargate and other alien technology. Despite Apophis's death in the beginning of Season 5, the Goa'uld Empire remains a major foe in Stargate SG-1 until the end of Season 8. The only influential Goa'uld in the last two seasons of Stargate SG-1 is the System Lord Ba'al (Cliff Simon), who is defeated in the direct-to-DVD film Stargate: Continuum. Anubis Arc After Apophis's defeat in the Season 5 premiere ("Enemies"), the half-Ascended Goa'uld System Lord Anubis (David Palffy) assumes the role of the primary antagonist of the show. This new villain possesses much of the knowledge of the Ancients