Thraetona conquered Dahaka, whom he chained to Mount Demavand who Kersasp was to kill at the end of the world, is important in the role as the universal king. When he divides the world between his three sons, Salm, Toz, and Erji, he grants them wishes. The first asks for wealth, the second for valiance, and the third for law and religion, for the khwarenah of the kavi, religious leader, lay upon him. So Erji receives the better part of the world, Iran and India, while Salm obtains the lands of the West, and Toz those of the East. This preferential treatment accorded to the youngest don caused jealousy within his brothers, and his death.
The importance of this myth is that it combines the Indo-European theme that the three brothers, with their wishes, chose closely bound social orders and the division of the world. A.G.H.
Grimal, Pierre, Larousse World Mythology, Secaucus, New Jersey, Chartwell Books, 1965, p. 201