Sylvans: The Sylvans were a peaceful race, and powerful in the ways of magic. They lived in small communities, separated from the rest of the world for most of history. This changed with the rise of the Orc Empire.
Arachnians: The Arachnians were the most technologically advanced race ever to exist in the world of Tressalia. Today, their scientific genius exists only in the form of the constructs.
Dwarves: The Dwarves were not one of the original races. They served the orcs during the time of their great empire and after it fell, they created a kingdom of their own, stealing much of the technology of the eradicated Arachnians. Religion was a central aspect to much of the dwarves' civilization. While they were monotheistic in the most part, they also worshipped the Calamities and made sacrifices to them regularly. They were also very oppressive, enslaving the elves and sacrificing human orphans "through Moloch".
Their kingdom fell with the arrival of Harold Hugh, who united many of the other races against them. Following the fall of their empire, elves and humans united to eradicate them, and were successful.