Origins
Earthen Races
When at last the Titans had sealed away the Old Gods, they set about the task of shaping to land to allow for life. Breathing life into the seabed, the mighty Sea Giants were born. This same breath of life reached into the very stone, and so came the Mountain Giants.
The two giant races shaped their respective homes, slowly forming a single continent within a great sea. The Mountain Giants had one fatal flaw that the Titans had not foreseen, however. Unlike their more 'living' counterparts, the Mountain Giants could not reproduce.
Rather than reject this first creation, the Titans chose to ask the help of the one Old God Lieutenant who had sided with them. Descending into the depths, they spoke to the benevolent Therazane, who had felt a connection with Eonar. She agreed to allow a race of creatures made of her flesh, with one condition.
Her condition was that she could allow her daughters to live on the surface. Eonar agreed, so long as they would help to maintain life rather than destroy it. So Therazane created the Earthen, while her daughters Myzrael and Theradras helped their younger brothers and sisters.
The creations shaped earth easily and efficiently. The only flaw in the system arose with their bodies. The digestive system of the earlier Earthen could only process stone, and this kept their minds from remaining intact. The unpredictable result was that the Earthen became unable to think above a basic level. The Titans sealed away most of these new 'Troggs,' but two clans escaped.
The first clan made way into the forests, where they could hide until someone decided to raze the entire forest. This clan was instead changed into true life, with mortal life and proper digestion. This allowed the Gnoll Clan to survive upon meats instead.
The Kobold Clan, the only other to escape, did so by hiding underground. That was the only place the Titans could seal the Troggs, and so changed this clan as well. The Kobold Clan gained intelligence, though not to the degree later versions of the Earthen would reach.
The Titans achieved this easily by merely severing the two clans from the Well of Eternity, the source of magic and life for the world. This was accidentally repeated with two later versions of the Earthen, which became the Dwarves and Gnomes when the Sundering split the continent.
The last of the Earthen Races came from Theradras. These two races were the children of her and Zaetar, first son of Cenarius. The Earth Princess was pregnant with six clans who were to live between the Earth Mother and Demigods. The Old Gods, enraged at the betrayal of Therazane, combined the might of their five evils and planned to corrupt the clans that were birthed. Though the first retained their noble heritage, the last five clans were corrupted by the Old Gods. These became the Centaur, who slew their father in the name of their masters, and were sent forever to hunt their pure brothers, the Tauren.
AN: I would just like to tell everyone now that related races are actually harder for me to do, since I need to make a logical connection. I can only hope the Earthen connection is good enough.