Un’Goro Crater was revealed to be the landing site of the Titans during the Ahn’Qiraj Solo quests. However, there are three known ancient Titan ruins that served as base of operations.  The Earthen (former rock-based ancestors of the dwarves) and the Stone Watchers of Norgannon hibernated for thousands of years within these three bases after the earthquakes of the Sundering affected their underground diggings:  Uldamar, Uldum and Ulduar.

The Explorers’ League Prospectors that came along with Jaina Proudmoore during the Third War, found important ruins in the Barrens by the excavation site known as Bael Modan(”Red Mountain”).  These titan ruins suggested the existence of Uldum far south at the Tanaris Desert.  However, until recently, Prospector Gunstan found Uldum.

Uldum is the second base of the Titans located in southern Tanaris.  Expect this instance to unveil a lot of new lore on races of Azeroth and the Titans. The first Titan base:  Uldaman—in Badlands—revealed the origin of the Dwarves and Troggs as degenerated versions of the rock-based humanoids: Earthen—created by the Titans.  When you grab the discs of Uldaman and bring them to Uldum and activate a pad on the left side of Uldum’s gate, the hologram of a Stone Watcher of Norgannon tells you that you need the Uldum coins-set along with the coins-set of Uldaman; as if it was a keychain, in order to gain access to Uldum.  The Stone Watcher of Uldum also said the Titans scheduled revisitation of Azeroth.  Read the quests below and check out the screenshots of the Stone Watcher of Uldum.

Quest related to Uldum

Portents of Uldum (horde) lvl 45

Ahh, it is fortuitous that you have come to me again.  Your revelations at the Uldaman dig site have certainly given us sages much discuss.  I was doing just that with one of the druids, Nara Wildmane, when it dawned on me that her past adventuring experiences may have some great importance as to the next step we need to take.

I would like for you to speak with her concerning her travels to the Valley of the Watchers in the Tanaris desert.  She waits for you on the Elder Rise.

Seeing What Happens (Horde) Elite lvl 45

Nara Wildmane – Thunderbluff

Bring the miniature platinum discs to the gates of Uldum in Tanaris and look for clues as to the connection between the two.

Sage Truthseeker and I would like you to take the miniature discs you found to the sealed gates of Uldum.  We… we aren’t sure what will happen when you do this.

This sounds risky, sure, we acknowledge that.  It might, however, do nothing.  You might need to use the discs on something.  Perhaps the doors unlock when you have the discs in your possession.  Be open to try anything, and be ready for anything to happen.

Learn what you can, then return to me. We will have much to discuss.

Portents of Uldum (Alliance) lvl 45

High Explorer Magellas – Ironforge

Greetings once again!  Your discovery inside Uldaman has set the Explorers’ League abuzz with excitement.  The League has been working to unlock the secrets of the miniature platinum discs you found.  Your fortuitous arrival here in the Hall allows me to share with you that we are quite possibly on to something!

Historian Karnik has uncovered some important clues as to the true origins of the Valley of the Watchers in the Tanaris desert.  He would like to speak with you as soon as possible!

Source

Warcraft: The Roleplaying Game Corebook – page 211