Dwarvish

The Lumin Dwarves first spawned the langauge back in the Lumin Realm. It is not clear how the language orignated, since it doesn't share any notable characteristics with any other language. Dwarvish is full of hard consonants and guttural sounds, and those characteristics spill over into whatever other language a dwarf might speak.
When the Stone Dwarves first emerged from their sanctuary to explore the new world after The Rupture, they soon adopted the Lumin Dwarves' language as their own, as many folk assumed they knew it already.