From WoWWiki
The Scarab Wall lies at the southern edge of Silithus, marking the boundary between the silithid-controlled desert and the ancient kingdom of Ahn'Qiraj. It is an impressive structure, including some sort of magical shield that also prevents creatures capable of flight to simply fly over it.
There is a World Event to open the Gates of Ahn'Qiraj.
While ingame, a player attains the rank of Scarab Lord when opening the wall, it is known that Shiromar was the one who rang the gong in lore. This potentially means that she is the Scarab Lord when it comes to the storyline.
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