Shahnameh by Abolqasem Ferdowsi — Read

Feraydun Divides the World Between His Three Sons

Then Feraydun brought into the open a plan he had kept secret. He divided the world into three parts: one part consisted of the West, another of China and the land of the Turks, and the third of Persia, the land of warriors. The first area he gave to Salm, whom he ordered to select an army and set off to the West, where he was enthroned and acclaimed as the Lord of the Western Lands. He made Tur the master of Turan, and gave him sovereignty over the Turks and the land of China. Tur selected his army and marched to his new home, where he was enthroned and his nobles showered him with jewels and acknowledged him as the Lord of Turan. When the affairs of these two had been settled Feraydun turned to Iraj, on whom he bestowed Persia and the lands of the Arabs. He gave him the crown and sword, the seal and ivory throne, because he was worthy of them. Each of the three princely brothers sat in state in his own kingdom, and wise men proclaimed Iraj as the Lord of Persia.