The pictures of hill tops explain that the Incas were hiding from something possibly a small militia. It was said that Francisco Pizarro took a small group of men and slattered the Incas.

pizzaro

Dear Royal Highness,
I am writing to you from Panama. The time is right to strike the Inca Empire.
The Inca are powerful, their territory stretches more than 2,500 miles north to south, and 500 miles east to west. But they are weakened by the bitter struggle between the half brothers, Huascar and Atahualpa, who both want to rule. You’ll remember the death of Huayna Capac five years ago divided the empire.
Also, the Inca have the most power of any Native American nation in the Western Hemisphere. They have made a network of stone roads connecting all the kingdom together, which makes communication swift, and these roads will make traveling for my army easier.
My plan is to take about 180 men with firearms from here in Panama to Peru. Once there, I plan to take Atahualpa prisoner and make him head of the empire. That would make me the real ruler of the Inca Empire.
So, King Charles I, that is my plan. I will let you know how it goes.
Your Humble Servant,
Francisco Pizarro

http://library.thinkquest.org/J002678F/pizarro.htm

This shows that the Incas were murdered by Francisco Pizarro.

http://www2.truman.edu/~marc/webpages/andean2k/religion/MachuPicchu01.jpg