From The Stargate Omnipedia
World once used as a slave labor camp of transplanted Humans
for the purpose of mining Naquadah
to fuel the needs of the gods.
The civilization eventually managed to conquer their oppressors and establish rule, continuing to send shipments of naquadah to the System Lords through the Stargate so as to trick the Goa'uld that their presence still thrives on the planet.
Workers still mine naquadah deposits, while a small number live above within the pyramid ship in the lap of luxury. When Pyrus the god slayer died, his daughter Shyla ascended to the throne.
HOME TO - Shyla's people
FIRST APPEARED - Need
Need - SG-1 visits P3R-636 and all members, with the exception of Jackson are taken underground to work in the naquadah mines.