P2R-111 was a planet in the Milky Way galaxy which was once visited by the Ancients who constructed a Stargate there. Later, the world was visited by SG-1 who assisted the Nox in capturing the renegade, Druana, who had taken a Goa'uld symbiote.
It was one of the many planets which was once visited by the Ancients during their time in the Milky Way galaxy, who planted the Stargate amongst a circle of standing stones. Whether or not they inhabited the planet is unknown but, if they did, then all evidence of their presence on the planet was gone by the time the Tau'ri built Stargate Command.
During the second year of the Tau'ri running Stargate Command, SG-1 visited the planet. While there, they were attacked by a group of cloaked Jaffa who were under the command of the Goa'uld symbiote which was inhabiting the body of Druana. The team was eventually forced back to the Stargate as they couldn't see who was firing at them, but they were saved by Anteaus and his group of Nox who unveiled the Jaffa before putting them to sleep.
After this, Anteaus explained to SG-1 that Druana had left her life quest and betrayed her people by allying herself with the Goa'uld, asking that SG-1 help them bring Druana back to her people. Though Colonel Jack O'Neill was turned down when he asked that the Nox share their secrets with the Tau'ri—as Druana had already shared them with the Goa'uld—SG-1 agreed to help the Nox hunt Druana down.
The two groups soon came across some more cloaked Jaffa who were guarding a cloaked Death Glider, which only the Nox were able to sense. After informing SG-1 that Druana was with this group, O'Neill threw a rock in the direction that the Nox were pointing, which hit off an object. Everything then uncloaked, and the Jaffa fired their staff weapons at the group. Before SG-1 were able to attack them, however, the Nox once again used their abilities to put the Jaffa to sleep.
It was only then that Druana revealed herself, now dressed as a Goa'uld. She informed the Nox that they should not have followed her and, although Anteaus tried to convince her to come back with them, Druana simply got angrier and told them that she cared nothing for their ways any longer. Through a short battle between Druana and SG-1, Anteaus was shot with Druana's staff weapon and Druana herself was incapacitated by O'Neill throwing a grenade inside her kara kesh's personal shield.
Once the battle was over, Lya and Ohper used their healing ritual to save Anteaus from death. After Anteaus recovered consciousness, he simply asked if Druana was okay; Samantha Carter quickly checked Druana's body and informed him that her symbiote would keep her alive while she healed. Although O'Neill then tried to convince the Nox to let them take Druana back to Earth so that she couldn't return to the Goa'uld, the Nox refused the offer and instead informed the group that they would take her back to Gaia and remove her symbiote. Before O'Neill was able to argue the point, the Nox once again cloaked themselves and disappeared.
After this, SG-1 left the planet but not before remarking that they hoped the Nox knew what they were doing otherwise they may have witnessed the death of one of the Four Great Races. (SG1: "2006 Convention Special")