For opening Ahn’Qiraj both Horde and Alliance have to collect thousands of supplies to aid in the war effort. You could turn these in at the War Effort bases (located at the Military Ward in Ironforge for Alliance, and the Valley of Spirits in Orgrimmar for Horde).
Each turn-in gives you Ahn’Qiraj War Effort Supplies, containing a green item equivalent to the level of the item you have turned in, and a number of signets ( Alliance Commendation Signet / Horde Commendation Signet), which can be turned in at Commendation Officers for reputation.
Both factions have to gather a total of:
90,000 Copper Bar (1 signet per turn in)
26,000 Purple Lotus (7 signets per turn in)
80,000 Thick Leather (7 signets per turn in)
17,000 Spotted Yellowtail (7 signets per turn in)
400,000 Runecloth Bandage (10 signets per turn in)
Alliance have to gather:
180,000 Light Leather (1 signet)
800,000 Linen Bandage (1 signet)
110,000 Medium Leather (3 signets)
33,000 Stranglekelp (3 signets)
14,000 Rainbow Fin Albacore (3 signets)
28,000 Iron Bar (5 signets)
20,000 Roast Raptor (5 signets)
600,000 Silk Bandage (5 signets)
24,000 Thorium Bar (10 signets)
20,000 Arthas’ Tears (10 signets)
Horde have to gather:
96,000 Peacebloom (1 signet)
10,000 Lean Wolf Steak (1 signet)
22,000 Tin Bar (3 signets)
250,000 Wool Bandage (3 signets)
19,000 Firebloom (5 signets)
60,000 Heavy Leather (5 signets)
18,000 Mithril Bar (7 signets)
250,000 Mageweave Bandage (7 signets)
60,000 Rugged Leather (10 signets)
10,000 Baked Salmon (10 signets)
Once supplies are collected, the ten-hour-long continent-wide event begins. Obelisks Resonating Crystal Formations reportedly appeared in Silithus, Tanaris, Feralas, The Barrens, Darkshore, Thousand Needles and Un’Goro Crater. These obelisks spawn different creatures to kill.
There are also 3-time limited delivery quests available in Cenarion Hold during this 10-hour event. Each quest rewarded 2 70, as well as Colossal Bag of Loot.