The Guardians of Hyjal are a faction of druids and warriors, united in their desire to protect the sacred Mount Hyjal and its protector spirits, the Ancients. Without a single leader, the Guardians tentatively follow the guidance of notable druids like Malfurion Stormrage and Arch Druid Hamuul Runetotem, as well as the Skylord Omnuron (leader of the Druids of the Talon) and Captain Saynna Stormrunner (leader of the Shadow Wardens). After the events of Cataclysm, the primary goal of the Guardians is to secure the aid of the five Ancients - Aessina, Aviana, Goldrinn (also known as Lo'Gosh), Tortolla, and ultimately - Cenarius.

Reputation

The Guardians of Hyjal will likely be the first faction you will start earning reputation in as soon as you enter the new Cataclysm content. They offer pretty much only the standard ways to earn reputation with them:

• Quests. All of the Guardian's quests are contained in Mount Hyjal, and you can start doing them as soon as you enter the zone - no prerequisites required. Assuming you complete the entire zone, you may be able to get all the way from Neutral to Revered just from questing.
• Tabard. When you hit Friendly with this faction, you will be able to purchase Tabard of the Guardians of Hyjal from Provisioner Whitecloud, who can be found inside that building under Nordrassil's roots. As long as you wear this tabard, monsters in Grim Batol and Halls of Origination, as well as all of the Cataclysm heroic dungeons, will award reputation with the clan. This method of reputation gain is called championing.
• (New in 4.2.0) Dailies. If you have completed the Hyjal quests leading up to Aessina's Miracle, you will have yet another way to increase your reputation with the Guardians. The Sanctuary of Malorne area of Hyjal will turn into a daily quests hub and will soon lead you to the Molten Front area, where even more quests will open up. Each one of those quest hubs will offer a significant number of quests, many of which will reward you with Guardians of Hyjal reputation.