Varok Saurfang's Horde is a faction of orcs who sided with Orgrim Doomhammer against the Burning Legion. They are very similar to the First War orcs, but, like Orgrim, they use shamans instead of warlocks. They control the majority of the land From Blackrock Mountain to Duskwood, with their only major rivals being The Southern Resistance, the Gurubashi Trolls, and the mysterious tower of Karazhan.
Their forces consist mainly of Blackrock Orcs along with various Ogre tribes. There is also a fairly large group of Bonechewer warriors present, presumably called to Azeroth some time after the Second War. The Sythegore arm also makes a cameo later on in the fight. Tainted Shamans are also a part of Saurfang's forces, which appear to be a different name for dark shamans
After the second war it would seem that they lost a massive amount of their holdings, notably Westfall, Redridge, and the Blasted Lands. It's not exactly known how they lost these lands, but it's most likely from a series of guerilla strikes from Varian's resistance coupled with the efforts of Khadgar. The two main bases of this faction are cut off, as Redridge disconnects Blackrock Mountain from the rest of the orcish forces.