Originating from the planet Earth, humans are a most common sight on Stargate-occupied planets. Thousands of years ago the Supreme System Lord Ra discovered Earth, from which the Goa'uld scattered humans throughout the galaxy. The humans of Earth are known by the Goa'uld and Jaffa as the Tauri.
Certain numbers of humans were genetically altered into Jaffa, humans designed for the purpose of carrying the larval form of the Goa'uld. The Goa'uld also impersonated the deities of ancient civilizations on Earth, to gain obedience and worship. Over the centuries, many planets inhabited by humans once under domination became devoid of Goa'uld interaction, permitting the humans independent development in the directions of their original cultures. Egyptian, Roman, Greek, and many other root cultures gradually began to spring up across the galaxy in their own unique forms. But many worlds still suffer from Goa'uld oppression and, consequently, are underdeveloped. The past millenia have been wasted for them by poverty under the power of Goa'uld lords and Jaffa soldiers. On Earth, the Tau'ri have unlocked the secrets of the Stargate and begun to explore the universe. The teams of the S.G.C. have found countless human cultures, and helped to liberate many of them from the Goa'uld. In so doing, the Tau'ri have taken their place on the galactic landscape.