The Lost City of the Tol'vir is one of the three 5-man dungeons in Uldum. On Normal-mode it is designed for level 84-85 players. The dungeon is populated by a faction of the Tol'vir, the Neferset--a mysterious race of "cat-people" created eons ago by the Titans to maintain and safeguard their research facilities in Uldum. The Neferset initially swore loyalty to Deathwing but after their betrayal, are now hostile to all.

Players battle members of the Neferset outdoors--the dungeon is designed to look like an actual abandoned Tol'vir city. It's also an excellent place for skinning. Players that turn in Tol'vir Heiroglyphics with Tol'vir Hieroglyphic are granted Tol'vir Secrets.

From the Blizzard Community site:
"The Lost City of the Tol'vir is the stronghold of the Neferset, a faction of the cat-like tol'vir who swore fealty to Deathwing in exchange for a cure to the curse of flesh, which had turned their rocky hides to soft skin. With the affliction expunged, the tol'vir have rebelled against their benefactor, although they remain irrevocably twisted and hostile due to the dark pact that they made.

The lost city is eminently defensible - bordered by crocolisk-infested marshes and surrounded by mountain peaks, it would prove difficult to invade even without the defending army. Worse, the Neferset are led by the being responsible for their newfound power - Siamat, the Lord of the South Wind and one of the mightiest servants of Al'Akir and Deathwing.

Though he is a mighty foe and unshakable general, Siamat's presence is also an opportunity. After invoking immense forces to strengthen and corrupt the Neferset tol'vir, his full powers are beyond him for the moment. A small group of truly powerful heroes might be able to infiltrate the city, and attack the Lord of the South Wind, striking a blow from which even the elemental cannot recover."