Dwarves
The Dwarves of Durin's Folk prospered in Erebor, and there are indications Gimli led a group of dwarves to Aglarond.
Mining expeditions were sent to Khazad-dûm where mithril was again mined, used to restore the gates of Minas Tirith, but Khazad-dûm was not immediately recolonized. There are, however, indications that a Durin the Last later did rebuild this Dwarven Kingdom, returning Durin's Folk to their ancestral homes.
Apparently the Dwarven race began to dwindle by the end of the Fourth Age, for their women made up less than a third of their population. Often, the women would not desire to marry, or want a husband that they couldn't have. Similarly, many Dwarven men were too engrossed in their crafts and did not have the time to take a wife and have children. Their ultimate fate is unclear.
Read more about this topic: Fourth Age