The Gemmondians were once the Aztecs of Earth who were brought to the planet by unknown beings, most likely the Goa'uld, from Earth. There they lived under a Byzantine legal system, in a society where every person knew their place. By 1997, however, they were a free people who SG-1 visited months before they visited Nasya. While there, SG-1 uncovered a conspiracy to seize land through the planet's legal system which earned them the gratitude of the locals.
This act would come in handy when, months later, the Tau'ri evacuated the Nasyans from their homeworld of Nasya due to an attack by Cronus. While they originally evacuated the people to Earth itself, they knew that they would not be able to keep them there and so Stargate Command sent SG-9 on a diplomatic mission to Gemmond on Colonel Jack O'Neill's suggestion. This brief mission with the planet's cultural leaders quickly led to the Nasyans having a new home on Gemmond, though there were some misgivings about finding a permanent place for them in the Gemmondians society.
The Nasyans, still bewildered from their first trip through a Stargate, made a second trip within a week and found themselves on Gemmond. Arriving on a step pyramid in the middle of Gemmond's largest city, the simple people were overwhelmed by what met them despite their previous trip to Earth. Seeing the streets stretch out from the great pyramid, lined with their colorfully-painted houses complete with walled courtyards containing lush jungle vegetation which the locals had tamed for garden use was too much for them and they soon became uneasy about their new home.
Soon after arriving on the planet, however, the Nasyans were introduced to the farming villages in the surrounding countryside which put them more at ease and was chosen as their new home. The Nasyans quickly made friends with the locals, learning of the different culture of the planet and adopting some of their traditions as well as introducing the Gemmondians to some of their own customs. Despite these promising signs, there was some friction between the two people partially due to these very cultural differences. An even greater problem than this to the two people was the Nasyans longer-than-average lifespans, which was a vast contrast to the Gemmondians foreshortened lives. It was hoped that the assimilation of the two species, as well as cross-breeding, would render this a moot point in a few generations. (RPG: "Friends and Foes: Stargate Season Two") (SG1: "In the Line of Duty")