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.
