I don't think his Incan sources would have approved of his purpose in this book: to demonstrate that the Spanish king had the right to rule them.
But as the devil saw that this door was shut, which he had begun to open to introduce by it dissensions and disturbances, he tried to make war by means of the very soldiers who resisted him, who were the same preachers. They began to make a difficulty about the right and title which the kings of Castille had over these lands. As your invincible father was very jealous in matters touching his conscience, he ordered this point to be examined, as closely as possible, by very learned doctors who, according to the report which was given out, were indirect and doubtful in their conclusions. They gave it as their opinion that these Incas, who ruled in these kingdoms of Peru, were and are the true and natural lords of that land. This gave a handle to foreigners, as well catholics as heretics and other infidels, for throwing doubt on the right which the kings of Spain claim and have claimed to the Indies. Owing to this the Emperor Don Carlos of glorious memory was on the point of abandoning them, which was what the enemy of the faith of Christ wanted, that he might regain the possession of the souls which he had kept in blindness for so many ages.
All this arose owing to want of curiosity on the part of the governors in those lands, at that time, who did not use the diligence necessary for ascertaining the truth, and also owing to certain reports of the Bishop of Chiapa who was moved to passion against certain conquerors in his bishoprick with whom he had persistent disputes, as I knew when I passed through Chiapa and Guatemala. Though his zeal appears holy and estimable, he said things on the right to this country gained by the conquerors of it, which differ from the evidence and judicial proofs which have been seen and taken down by us, and from what we who have travelled over the Indies enquiring about these things, leisurely and without war, know to be the facts.
(That bishop would be Las Casas, about whom many of us have much more sympathetic views.)
Inca Yupanqui re-invented the Assyrian approach to pacifying his rebellious empire: Chapter XXXIX: mitimaes--population transfers.
His son expanded the empire more, and tried his hand at searching for gold to the West (very much like some others to his east were starting to do). "Tupac Inca navigated and sailed on until he discovered the islands of Avachumbi and Ninachumbi, and returned, bringing back with him black people, gold, a chair of brass, and a skin and jaw bone of a horse. These trophies were preserved in the fortress of Cuzco until the Spaniards came. ... The duration of this expedition undertaken by Tupac Inca was nine months, others say a year, and, as he was so long absent, every one believed he was dead." "Black people?" Fiji is probably well over 5 months travel to or from, which doesn't leave a lot of time to go exploring when you get there. Maybe some of the Polynesians looked black to the Incas.
The Incan kings are credited with remarkably long lives: Pachacuti Inca Yupanqui "laid his head upon a pillow and expired, giving his soul to the devil, having lived 125 years."
Without money, the Incans had to come up with other ways of rewarding conquerors:
"Tupac Inca ordered the seclusion of certain women in the manner of our professed nuns, maidens of 12 years and upwards, who were called acllas. From thence they were taken to be given in marriage to the Tucurico Apu, or by order of the Inca who, when any captain returned with victory, distributed the acllas to captains, soldiers and other servants who had pleased him, as gracious gifts which were highly valued."
His introduction to the history has to be read to be believed. He starts way back with "Noah and his wife Terra or Vesta" and includes Hercules and Atlantis.
If that doesn't entice you to read it, I don't know what will.