Star system once home to a secret Tok'ra base, under the command of Malek. The base was discovered by Anubis, who launched an attack and forced a harried evacuation. Malek and his people used the Risa Stargate to dial the Alpha Site, where they found refuge among their Tau'ri allies.
Jacob Carter was present when the attack occurred, and risked his life to stay behind until the last possible moment in order to disable the Risa gate's dial-home device -- setting an explosive charge equivalent to a tactical nuke before escaping through the gate.
The Tok'ra had tried to dial Earth first, but the Earth gate was active at the time.
It is not known if any other planets in the Risa System are populated, but the Tok'ra tend to establish bases on unoccupied worlds.
Allegiance - Jacob/Selmak, Malek and several other Tok'ra, along with members of the Tau'ri, escape a downed Tok'ra base in the Risa System.