The Dev Eradication of the Sesha Dragons.

The devs. They just couldn't get over their prejudices. Their alliance with the sesha dragons had gone on for decades. Not every dev was comfortable with this, but together the devs and sesha dragons were unbeatable. Elves, ameshas, and qui-lahks in the region learned to leave them alone. They were terrified of the giant cobra dragons. They could not make any sense of the dev's alliance with them, and struggled to figure out ways to fight them both as they each required completely different strategies. Eventually they abandoned the territory, and left the devs and sesha dragons in peace. That peace is what led to the violent dissolving of the alliance.
No longer needing the fear inducing sesha to fend of enemies, the old doctrines and beliefs about dragons began to crop up for the devs. At the time the sesha dragons were almost treated like royalty. These beasts were allowed to roam freely in the dev nation. It was and had been a great arrangement for the sesha. Things really started to change when devs who were closest to the dragons began to change, and the devs who always questioned dragons saw this as proof of their evil nature. When the great warrior Gaorda saw this happen to his beloved cousin, Kallini, he took action. He told himself that she had been poisoned by the dragon's. He gathered like minded people and started a propaganda campaigns against the sesha dragons that took off very quickly. After being allies for decades, everything fell apart so quickly. The sesha were already surrounded by devs when the tide turned against them. They fought as dragons do, but the numbers and odds were against them. Gaorda killed the sesha king Irath, and in retaliation Kallini killed her cousin Gaorda. Decades of hunting and fighting later, and the last of the seshas were exterminated.
They really were extraordinary beasts. The loss of their kind is one of Adijari's most terrible tragedies.

Learn more about the Dragons of Adijari in

The Secret of the Zipacna Dragons