From the introduction:
"In the dark days, war on a scale never seen before covered the material plane. Calacha the Black Flame had achieved power like no other mortal. Desolated strips of land were left behind where the archmage and his armies walked. Many tried to oppose Calacha, but even a final alliance between humans and elves stood no chance. In the end, a desperate trap was set. A rumor of a source of eternal life lured the mage deep into the Jungle of Alara, but when he reached it, time froze. Supposedly, Calacha still stands there today, suspended in time. But people feared some of his men would find the mage and end the spell binding him. The jungle needed a guardian, with a lifespan long enough to outlive any remnants of Calacha's legacy. And so it came that the first guardian of Alara was the vampire Yar Al'Jacquen. An agreement was reached, where Yar would guard over the jungle, and in return mortals gave him blood willingly. Over time, the world forgot about Calacha, but Yar Al'Jaqen's keep grew into the city of Tath Mordra, with the remnants of Alara at its heart. Now, humans and vampires live in peace in this unique metropolis where anyone is welcome…"
- The Tale of Tath Mordra