The mythology of the Stargate franchise is the historical backstory of the Stargate premise, which centers around xeno-mythology as experienced by humans during episodic contact. In the fictional universe of the franchise, the people of Earth have encountered numerous extraterrestrial races on their travels through the Stargate. In addition to a diversity of alien life, there is also an abundance of other humans, scattered across the cosmos by advanced aliens in the distant past. Some of the most significant species or beings in Stargate SG-1 are the Goa'uld, the Asgard, and the Replicators. Stargate Atlantis, set in the Pegasus galaxy, introduced the Wraith and the Asurans. One of the most influential species in Stargate, the Ancients, have moved on to a higher plane of existence. The Extraterrestrial beings speak the English language and do not appear to be too different from the english language itself. This further develops the plot by making alien communication far easier. Stargate SG-1 (1997–2006) explains the human population in the Milky Way galaxy by revealing that the alien Goa'uld transplanted humans from Earth to other planets for slave labor. Many of these populations were subsequently abandoned, often when deposits of the precious fictional mineral naquadah were exhausted, and developed into their own unique societies. Some of these extraterrestrial human civilizations have become much more technologically advanced than Earth, the in-show rationale being that they never suffered the setback of the Dark Ages. The most advanced of these humans were the Tollan, although they were destroyed by the Goa'uld in Season 5's Between Two Fires. The human populations of the Pegasus galaxy are the product of Ancient seeding. Few human races in Pegasus are technologically advanced, as the Wraith destroy any civilization that could potentially pose a threat. There are also large numbers of humans in the Ori galaxy, where they empower the Ori through worship. Franchise-spanning mythology The film Stargate (1994) establishes that five thousand years ago, the god Ra transplanted Earth humans throughout the galaxy via the Stargate. As a result, the people of Earth rose up against him, and buried their Stargate. The modern history of Earth and the Stargate begins when it is unearthed in Egypt in 1928. The device is brought to the United States in 1939 to keep it out of Nazi hands and eventually installed in a facility in Creek Mountain, Colorado (Cheyenne Mountain in Stargate SG-1). In the