The Omeyocan brought a group of people from Earth to the moon by crystal skull, but when the Goa'uld discovered the moon they their Aztec slaves. The Aztecs killed the entire population and took over the moon and built their civilization there.
Fifty years before the modern Tau'ri arrived, the Goa'uld had abandoned mining for naquadah on the moon when it was depleted. In 2005 SG-10 and another team on the moon conducted a geological survey for geothermal naquadah. The SG team had to leave the moon when several earthquakes wounded the team. The Goa'uld returned to the moon when the locals would sacrifice to their goddess. The moon was about to leave its orbit and break apart, and only 250,000 of the people managed to get to another world by using a crystal skull. (SG1: "City of the Gods")