There has always been tension between the humanoid Titans of Ankhisteia and the bestial Titans of Bahamut.
After the previous titan wars - long before The Ascend - it was decided that neither side should interfere in the affairs of other Titans, that another war could pose a great threat to the mortal races and the entire world.
The agreement was kept for centuries until Horas, without known provocation, attacked and killed Jörmun, son of Ormr. He slew the World Serpent where Trypophis flows into the sea, impaling it with his sword Ashrune.
When Ormr learned of the meaningless death of his son, he confronted Horas. The latter seemed not to be master of his thoughts and attacked Ormr in a blind rage. Ormr barely escaped with his life and swore revenge.
Ormr then returned with his swarm of blue dragons. His twin brother Poadois, the Red also came to the rescue and together they destroyed Horas south of Essios Grove, who shortly before had strangled Kathura, youngest daughter of Ormr and thrown her remains into the ocean. This significantly worsened the atmosphere between the two factions of Titans.
Emissaries of the mortal races, led by Zethos, champion of the humans of Zeantis, tried their best to prevent a war between the Titans. But in the end it was the humans who started the war, when the occultist Zahiba of Dreya attempted to revive the body of Horas to create a powerful undead weapon, which the siblings of Horas assumed to be a secret revenge by the dragons.
A war broke out that lasted 33 seasons. During its course, numerous Titans fell. Bakazcoz and Vovaar, children of Horas, who attacked the Hoard of Poadois and wiped out most of its red dragons, were slain in a great battle. Ankhisteia then interfered, pulverizing a significant chunk of the continent. The land that was once called the Prairie of the Titans became a torn open wound in the center of Drimea, filled with a gaping desert.
Poadois, enraged over the decimation of his offspring, prepared to attack once again. With the help of the blue dragonflight and several of the other Elderdragons, they succeeded in destroying Ankhisteia. In this cataclysmic battle, many dragons and giants fell. In her last breath, Ankhisteia unleashed yet another gaping wound throughout the land. Akuos and Haemar, children of Poadois, whose remains can still be found in the Valley of the Dead, fell victim to this final attack.
After that, peace returned. The mortal races, who suffered greatly from the devastating battles of the Titans, were finally able to break through to them, and Zethos, the bringer of peace, has been hailed as a hero ever since. As a sign of peace, three gigantic swords were forged by the Titans, which have since lingered on the Mound of Sorrow, symbolizing truce between the two Titan factions and the mortals.
Tyrar, God of Death and eldest son of Ankhisteia, formed Iscaron, the Soul Tree, from the remains of his fallen mother, which stands in the north in the Valley of the Dead, shrouded in a carnivorous mist that is meant to protect the essences of the fallen Titans from power-hungry marauders.