From WoWWiki

The Convocation of Silvermoon, also called the Council of Silvermoon or the Silver Circle, was a ruling body of the high elven realm of Quel'Thalas, along with the Sunstrider Dynasty. Governing from the capital of Silvermoon, the Convocation was comprised of seven great high elf lords, who vowed to watch over and protect the lands from the Burning Legion and other threats. The Council was wiped out when Arthas Menethil razed Silvermoon during the Third War. After the attack, the last remaining members of the council were Kael'thas Sunstrider, who was in Dalaran during the attack, and Dar'Khan Drathir, who betrayed Quel'Thalas to the Scourge in order to gain more power for himself. After returning to the devastated elven lands, Kael'thas never revived the Council, but rather went on to become the sole ruler of the blood elves.