Tantara was a kingdom at the time of the Mage Wars. Leodhan was the High King, and Urtho was the Archmage. The territory of the kingdom encompassed what is now the Dhorisha Plains, much of the Pelagirs and Rethwellan, and parts of Valdemar.
It was the last kingdom to come under attack from Ma'ar. As with previous land he had conquered, Ma'ar began by trying to destroy the central government, sending his army to invade in the midst of the resulting chaos. In the case of Tantara, this took the form of a fear spell that was triggered in the royal palace in the middle of the night. Most of the nobility fled, and many of them refused to return out of shame for their supposed cowardice. The High King was found hiding in a wardrobe. He left the palace shortly after, refusing to return. While this portion of Ma'ar's plan worked perfectly, he had not counted on the Lady Cinnabar.
A Healer, Cinnabar slept under full Shielding and was unaffected by the spell. When she found the palace all but deserted the following morning, she immediately brought in Urtho, the Mage of Silence. Urtho quickly took control and began organizing the armies. Using his network of permanent Gates, Urtho was able to send the armies where they were needed to repel Ma'ar's attacks, bringing them back to their camp at the base of his Tower each night.
Unfortunately, Ma'ar had simply grown too strong for the armies of Tantara to fend off. Knowing they were losing, Urtho began the evacuation using the permanent Gates. In the end, the people were saved, but the land was entirely destroyed by the magical Cataclysm that ended the war. One of the explosions was centered on Urtho's Tower. It is now the site of the Dhorisha Plains. The other explosion was centered on Ma'ar and his forces, who had taken over the royal palace of Tantara. That location is now Lake Evendim.