From Halopedia, the Halo wiki
The High Gathering is a meeting between various Sangheili officials that has at least taken place once in late 2559, three days after the Razing of Oth Sonin. The meeting included the high kaidons of several Sangheili colonies as well as Arbiter and Swords of Sanghelios leader Thel 'Vadam.
At the meeting, 'Vadam proposed the Concert of Worlds to the other officials, hoping to further unify the Sangheili. No agreements between any of the officials could be made at the meeting, with 'Vadam suspecting that many of High Kaidons were satisfied with Created rule, particularly when it came to Cortana's pacification of the Jiralhanae. After the meeting, 'Vadam was frustrated by the rejection and lack of progress.
List of appearances
- Halo: Outcasts (First mentioned)
- Halo: Outcasts, chapter 1