Sarmiento records that Inca Viracocha named his illegitimate son Urco heir, fled the Chanca attack, and died stripped of his property after his other sons killed Urco

Pedro Sarmiento de Gamboa's 1572 history, compiled from the sworn testimony of Inca lineages, records that the Inca Viracocha had four sons by his wife and two by another woman, Ccuri-chulpa. In old age he named one of the latter, Inca Urco, as his successor "without regard to the order of succession", because he was fond of Urco's mother. Urco's descendants later said he was legitimate; everyone else said he was not. When the Chancas marched on Cuzco, Viracocha fled the city with Urco. His legitimate son Cusi Inca Yupanqui stayed with seven chiefs, defended Cuzco and won. He sent the enemy spoils to his father to tread on as a sign of victory. Viracocha said Urco should tread on them, because Urco was to succeed. The messenger refused and went back. Cusi took the name Pachacuti and began to give away the spoils as the new ruler. When Urco gathered men in the Yucay valley, Pachacuti's brother Inca Rocca hit him in the throat with a stone, and his brothers caught him in the river and killed him. Viracocha refused to see Pachacuti. Sarmiento writes that he died of grief, "deprived and despoiled of all honour and property". Gonzalo Pizarro later dug up his body for its gold and burned it. The Indians hid the ashes in a vase, which Polo de Ondegardo later found.