Why Chimor or south Peruvian civilizations did not capture the Incans?

Question

Jared Diamond asked in his treatise on the fates of human societies why it was not the Incans who captured Spain, but the other way around. The answer - guns, germs, and steel - seems to largely make sense. But what about the Conquered as Conquerors in their own right?

The Incans started out as a humble tribe along Lake Titicaca and ostensively possessed no technological or agricultural advantage over other Andes cultures. Pharaoh had his pots and granaries. Alexander of Macedon had his horses and chariots. King Charles had his microbes and metalsmiths. And Pachacutec had? It was without the aid of a superior food package (neither potato nor maize domestication began with them) nor superior beasts of burden (nor camelid domestication) nor superior weapons (they were still a Bronze Age culture) nor superior immune systems that the Incans forged 3000 km Tahuantinsuyu over the heads of the Chimu and many other Andes civilizations and across a diverse set of climates. How?

Answer 1

Those who live at lower altitudes have difficulty coping at higher ones, due to the lower amount of oxygen available in the air, (lower atmospheric pressure) and are just not competitive, physically, with those born and raised there. High altitude peoples have adapted, partially through natural selection, which only takes 30 - 40 generations to create a marked difference, to have large lungs, and they may also have had more h(a)emoglobin in their blood, and/or a higher proportion of red blood cells, to transport the available oxygen. They had another significant advantage: a potent central nervous stimulant in the Coca plant, (the source of cocaine) which the natives continue to consume to this day, to ward off the effects of altitude sickness, fatigue, and hunger. They also had the llama, organisation, and the knowledge that they had to be united, to survive against the formidable lowlanders.

Answer 2

It is possible that they had the same thing going for them that the Romans had - ORGANIZATION - a united and organized front against small scattered, insular tribes.

Another possible advantage would be the harsh terrain they lived in.  As well as just needing to develop superior physical strength in order to live at such high altitudes (living in the thinner atmosphere would naturally develop more stamina), the remoteness and high positioning of their cities would certainly have discouraged invasion from any contemporary local source.

It is pretty well suspected that the only reason the Spanish finally got the best of them was that, like the Aztecs to the North, they failed to recognize the white-skinned strangers as a threat till it was too late.  (The Azetcs had a bearded, fair-skinned God named "Quetzaocoatl", and the Incas had an equivalent deity named "Viracocha".)

The incas would have made no such mistake in regards to another "local" tribe, though.  

Had it not been for that singular bizarre c***k in their socio/cultural armor, even the Spaniards might not have gotten to them.