- Not to be confused with Thas'talah.
Shortly after the Highborne exiles created the Sunwell and founded the kingdom of Quel'Thalas, the well's magic began to radiate outward through the surrounding woods, and the forest's oldest tree began to absorb its energy. The massive tree was named "Thas'alah", and from its enchanted branches, the entire region seemed to bathe in the glow of an eternal spring.
To protect themselves from attacking Amani forest trolls, the Highborne created a series of monolithic Runestones that both acted as wards against intruders and hid the elves' arcane magic from the Burning Legion. The wards succeeded in keeping the elves' enemies out of Silvermoon City partly due to their anchor: the elven arcanists had linked the Runestones to Thas'alah, tying the power of natural magic to their arcane spells. However, the tree's power could not keep the Highborne safe when they left the city.
Years later, during the Troll Wars, the fighting order of rangers was founded, led by the first Ranger-General of Silvermoon, Talanas Windrunner. The leaders of Silvermoon declared that their champion be given a weapon befitting his new status, and so a trio of artisans joined together to create a great bow for Talanas. They carved its body from a limb taken from Thas'alah and infused the wood with the waters of the Sunwell, causing the weapon to harden and become nearly indestructible while still maintaining its connection to the natural magics of Thas'alah. When it was retrieved from the Sunwell, the bow radiated power. Talanas was humbled by the gift and named it Thas'dorah, "Valor of the Forest".
- An early concept map for World of Warcraft depicted a World Tree in the middle of Quel'Thalas. It could have been the later inspiration for Thas'alah.
According to legend, Thane Ironstar of the Dark Iron dwarves carved his shield from a sacred high elven tree and then enchanted the item to turn it hard as stone. If the legend is true, it could have been Thas'alah.