The Mission to the Valley of the Jedi on Ruusan was carried out by Kyle Katarn during the Disciples of Ragnos crisis in 14 ABY.
Luke Skywalker sent several Jedi to places where he felt a strong connection to the Force, after Alora sliced into his records. The objective of the mission was to investigate cult presence on the planet. He directed Katarn to carry out the investigations of Ruusan's Valley of the Jedi.