A peaceful planet occupied by a relatively primitive people, the Byrsa. The population was with the regular arrival of the Goa'uld, who used Cartego as a primary target for harvesting hosts for implantation.
Cartego's population is sheltered at the base of a mountainside where many caves beckon to the Byrsa when the planet is invaded. Called the "hiding," these caves not only provide their places of sleep, but are used when the chevrons ignite blood red, signaling the arrival of the incoming Goa'uld. The Byrsa flee into all directions and take refuge in these caves.
For some time Apophis himself used the planet to harvest hosts. Teal'c, while serving as his First Prime, was fully aware of the Byrsa's only defense, but did not divulge it in the hopes that more would be saved during each harvest.
Cor-ai - SG-1 gates to Cartego, where Teal'c remembers the world during his time as First Prime of Apophis -- and he is not the only one who remembers.