From publisher blurb:
The Yuan-Ti are often portrayed as sadistic, malevolent creatures intent on dominating the world at all costs. The very image of the scaly, humanoid reptiles with venomous fangs and wicked, yellow eyes fills most people with dread. For Game Masters, this makes them the ideal antagonists: Alien in both appearance and motivation, they can easily, and with little explanation, be dropped into any campaign or adventure as the fiendish masterminds behind virtually every conflict the characters run up against.
They are a society of long standing tradition, placing as much value in erudition as other cultures might place in martial prowess. Players and Games Masters alike will discover a wealth of possibility hidden within the vast empire of the Yuan-Ti. For the inquisitive, there is a new culture to study; for the diplomatically savvy there are new alliances and treaties to be negotiated; and for the bloodthirsty, there are new foes aplenty to kill.