History
At some point they ended up in Hel, the underworld of the Asgardian cosmology. They were released, along with a number of other dead creatures, when Malekith instigated a revolt in the underworld.[1]
Miscellaneous
Level of Technology
They commonly use simple weapons such as clubs made of ice and snow.
Trivia
The Ice Dwarves are collosally big when compared with human-sized beings, but still small when compared with Ice Giants.