I can believe it. I had a friend from there, but do you have a “short” history of the Inca? What forced them into these mountains, just assuming that it would be easier to develop the lowlands.
Were the surrounding tribes that hostile and effective?
The population was rising in Peru, and there was land for the taking, so the “Incas” took it. They didn’t have the kind of problems with the neighbors that the Aztecs had manufactured for themselves — the Spanish found it easy to get their neighbors to turn on them, after their near-miraculous escape from Tenochtitlan and the pursuit by an angry Aztec army. Because of one lucky shot, in which a Spaniard killed one of the main leaders from a great distance, the Aztecs thought they were doomed, and turned tail.
The Incas had a widespread empire with a number of tribute tribes. And yes, it helped that they did not consider their neighbors their “bread” and eat them. Nevertheless, when the Spaniards decided to conquer them and steal all their gold, it is thought that this site was used as a last hidden retreat.
My mother went there when she was in her 70s, I am not sure exactly how she got there, but she was a tough old bird. ;-)