The Jedi Assembly, a somewhat informal administrative group, was founded within the Jedi Order on the planet Ossus. This group, which convened each day for meditation and discussion, consisted of the most knowledgeable Jedi Masters of that time. They not only talked about what was happening within the Order but also gave advice to Jedi Knights and provided guidance to anyone who asked for it. This group was dissolved after a large number of its members were killed during the uprising in 3996 BBY. Shortly after this, the Assembly was re-established as the Jedi High Council, a more structured executive body of the Order that would guide the Jedi until it was finally disbanded in 19 BBY.
This assembly was composed of several reliable Jedi Masters who gathered daily on both Ossus and Coruscant to meditate and deliberate on the philosophies of the Jedi. The Assembly, intended to establish a flexible hierarchy within the Jedi Order, included Jedi such as Ood Bnar, Vodo-Siosk Baas, and Thon, and was led by Master Odan-Urr for a period of 600 years. Their meetings took place in a circular room that was sparsely furnished, featuring only a stone protrusion at its center. A large Force crystal was embedded in this stone, serving to concentrate the Force's energies within the chamber.
In 3996 BBY, many members of the Assembly were brutally murdered, either by their own students during the uprising led by Exar Kun, or during the attack that preceded the devastating Cron Supernova, which rendered Ossus largely uninhabitable. A decade after the devastation of Ossus, Master Nomi Sunrider convened a convocation of all Jedi at Exis Station, where she assumed leadership in determining the Order's future. To replace the Assembly, she established a new Jedi High Council, designed to govern the Order with greater strictness in an effort to prevent further Jedi from succumbing to the dark side of the Force.