The Three Sons of Feridun

According to the legendary history, Feridun had three sons. To Selm he gave the West, to Tur the East (henceforward termed Turan); while to his youngest son, Erij [Iraj], he promised the throne of Persia after his own death. This arrangement, not unnaturally, was displeasing to the elder brothers, who threatened to invade Persia to make good their demands. Erij visited his brothers and offered to resign his rights to the throne, hoping by this means to avoid civil war during the last days of his father's reign. Selm and Tur, however, resolved to put Erij to death, and refused to listen to his pathetic pleading for life [...] Erij was murdered and his head was embalmed and sent to the aged Feridun, who was unable to avenge the crime. Some years passed and Manuchehr, son of Erij, grew up and "attended by armies and clad in steel", killed both his uncles in single combat.

Encountered an even shorter precis of this myth in My Name Is Red. Found this one on the Iransaga website. I wonder if King Lear derived from this myth or if both derived from an even older story -- or if I'm seeing connections that don't exist.