The Mung start in the Ironfrost Glacier province, just above Dark Elven Naggaroth. They spread Chaos corruption in all of their provinces like any Norscan faction. They start on bad terms with the Dark Elven factions around them, and will usually declare war on Naggarond sometime during the first few turns. If playing as Naggarond, the player may have to conquer them at some point. They are also known to colonize as much of the northwestern provinces of Naggaroth (which are mostly comprised of ruined settlements) as possible. That being said, their settlements are generally bad climates to the Dark Elves and are better off being razed or occupied and allowed to rebel, as maintaining public order in the province is difficult in the early game.
In Warhammer's lore, Mung is not a Norscan but a Hung clan. The Hungs are one of the three peoples of the Nordic tribes, along with the Norscans and the Kurgans.