Yuan-Ti - PC

Long ago, the human civilization known as the Yuan-Ti ruled an empire so vast and wealthy that all looked at it with wonder... and fear. The nobles of the Yuan-ti gained a great amount of opulence and power but wanted more. They turned their focus onto mysticism. They pledged their fealty to the Serpent Gods around them, namely Dendar, Merrshaulk, and Sseth. The Gods granted them the power, strength, and serpent-like alterations to their followers in exchange for the simple sacrifice of blood. Fueled by their desires and their serpent patron's thirst, the Yuan-Ti gathered up their slaves by the thousands, slaughtering them on the multi-tiered temples dedicated to their insatiable gods. The rituals performed gave way to strange alterations to the Yuan-Ti peoples' bodies. Serpent-like limbs replaced arms and legs. Sharp teeth, poisonous like a snake's protruded from their mouths. Their pupils became slit, and in the most extreme cases, entire heads transformed to be that of a serpent, some have as many as six heads.
The Yuan-ti warred against anyone in their pather in their ever-long search for more sacrifices to their Gods. Entire battalions would rather die on the battlefield than be captured for the cruel sacrifices enacted by the Yuan-Ti. City after city fell in the wars against the serpent peoples. The continents of Yuani, Xuxin, and Nohola were all under the rule of the Yuan-ti, except for the cities of the Black dragons. There was a long-standing non-aggression pact between the Yuan-Ti and the Black Dragons, but after a lone group of Dragonborn troops had been captured and sacrificed, the end of the Yuan-Ti empire had begun.
Upon tasting the Dargon-Kin blood, the Serpent Gods became voracious. The Gods commanded the Yuan-Ti to send the might of their armies upon the Black Dragon kind, splitting the Yuan-Ti forces even further. The Black Dragons had not faced such a powerful enemy since the Great War and had not been prepared for an invasion. The Dragons retreated back to their capital, Othim Bane, and in a desperate move, sent their Kenku messengers out with correspondence asking for aid to their Chromatic kin. Only the White dragons responded and they said that they were afraid to be involved in another global conflict. It came as a shock to the Black Dragons when a message came from the Bronze Dragons to the North. Just a few centuries earlier, the Bronze and Black were mortal enemies, fighting for control of Eraterna, but unbeknownst to the Black Dragons, the Kenku had sent out messages hoping some sort of reconciliation could be reached. The message ensured the Black Dragons that the Bronze would set up a counter-offensive from the North with the combined forces of the peoples of Xuxin. With the Yuan-Ti forces pulled back to the Northern front, the Black were able to drive out the Yuan-Ti out of their territory and the two forces finally brought an end to the great Yuan-Ti empire.
The Yuan-Ti people can still be found throughout the lands of Eraterna, small villages of the survivors are strewn where their old empire laid. The Yuan-Ti capital was set up as the last refuge of Yuan-Ti people and the Black Dragons have vowed to oversee it to ensure no new empires should arise. The Yuan-Ti are always scheming though. Their noble, their peoples, and most of all their Gods look forward to the day their empire might rise again.