Dwarves

When the breaking occurred, the underground was sealed away from the world above, the underground was left with very few means of accessing the surface. Some dwarves by the edge sought to rebuild the connections between their cities and the surface world, others retreated deeper to the underground, founding new deep cities in the newly expanded caverns of the underdark. This split remains between the various dwarven cultures like the hill and mountain dwarves, and the gray dwarves, the duergar, deep in the underdark.