Belaur was the oldest son of the Stag King of Athalantar, Uthgrael Aumar. At his father's death in 216 DR, he proclaimed himself king; however, most of his brothers opposed him, starting a civil war.
Belaur in the end defeated his brothers with the decisive help of a group of wizards recruited by him, the magelords. However, the magelords proved themselves more powerful than Belaur and soon assumed control of the kingdom.
Thus Belaur ruled in name only, but people considered him responsible for the situation. In 240 DR, his nephew, Elminster Aumar, started an insurrection against the magelords. Elminster killed Belaur.