> If different varieties of potatoes grow differently at different latitudes (I don't know, I'm not an expert), then it doesn't really matter how productive a crop the potato is.
The introduction of the potato reshaped Europe and boosted European population by 25%. https://www.youtube.com/watch?v=xROmDsULcLE
> The Inca didn't have horses, only llamas. Horses were militarily very important.
The horse is a valuable animal given a favorable terrain. But with elevations such as the Andes, a horse is not as useful. And wheels are a similar story.
Horses were useless in the Battle of Ollantaytambo, where the Inca used terraces to their advantage, but proved very useful in the defense of Lima (a coastal city) against the forces of general Quizquiz.
> After initially being defeated, acquiring guns, steel, and horses from the Spanish and then rebelling against them.[1]
The Mapuche did not "acquire" guns or steel. They could not manufacture them, but they became aware of them and developed techniques against them.
They knew harquebuses were not waterproof, and if they would prefer to engage during rainy weather. They knew that trying to pierce through steel was ineffective, so they prefered to stun.
They also became aware of the usage of cattle and they frequently raided cattle and set structures on fire.