Argus was the original homeworld of the Eredar (and hence the Draenei, who are physically identical to the original eredar). It was apparently a utopian world whose inhabitants were both vastly intelligent and highly gifted in magic. Argus was ruled by a triumvirate of the greatest and most powerful eredar mages: Kil’jaeden, Archimonde, and Velen. It is possible that they ruled from Mac’Aree, the most sacred of the cities on Argus, according to Jessera of Mac’Aree. Eventually, Argus attracted the attention of Sargeras. The Destroyer offered the Eredar a deal: in exchange for their loyalty, he would give them power undreamed of by all races. Kil’jaeden and Archimonde were quick to accept the offer, but Velen had a vision of the future: the eredar would be transformed into demons, under the rule of Sargeras. His advice to Kil’jaeden and Archimonde went unheeded, and he desperately sought a solution to this dilemma. Eventually, Velen was contacted by the Naaru, and he fled with his followers, renaming his people the Draenei, or Exiled Ones.

Kil’jaeden, Archimonde, and the rest of their race became the feared, insidious sorcerers and tacticians of the Legion.

It is unclear whether the world of Argus was destroyed by the Eredar’s sudden demonic powers (as implied by previous lore), or if it survived their transformation. If Argus still exists, it is certainly a stronghold of the Burning Legion, possibly their headquarters. Rise of the Horde leans towards this interpretation, though nothing is explicitly stated.