Shards of the Shattered Pact: Seowyn's Crossing
The Yuan-Ti are a race of decadent snake-men who inhabit the continent of Velnar. They first inhabited only the eastern jungles of Velnar, but their Empire slowly spread westward, causing humans native to Velnar to make exodus to other lands. This is what caused the spread of humankind across Tol.
The Yuan-Ti are known to capture humans, enslaving them and using them in foul breeding programs. Some Yuan-Ti, called Purebloods, look almost human, except for some minor reptilian features. These act as diplomats with the remaining human peoples of Velnar. The so-called Halfblood Yuan-Ti look more reptillian and are generally hidden away deep in Yuan-Ti cities, guarding temples and acting as a hidden army. The most monstrous Yuan-Ti called abominations, seem to be made up of numerous serpents, the way an elemental is made of fire or water.
The Yuan-Ti worship a foul serpent god named Szathusa and believe they are destined to destroy the world. Although they don’t get along well with anny race, they reserve a special hatred for the insectile thri-kreen with whom they battle for territory.