There still finding ruins in the Amazon, cities that supported up to 1m people in the 15 century.95 % of the indigenous population in North and South America were killed off by Old World diseases that Europeans brought over.
Imagine a society that existed for thousands of years completely collapsing and only 1 in 20 surviving without a single bullet.
Can what follows afterwards even be called a war?
"The model also showed that people wouldn’t necessarily have built close to rivers, an idea which runs counter to modern assumptions. It revealed that there are likely 1,300 geoglyphs and villages in a 154,000 square-mile swath of Southern Amazonia—two-thirds of which haven’t been found yet.
The computer model also predicted population densities that were much larger than expected. The team now thinks that between 500,000 and 1 million people once lived in just seven percent of the Amazon basin. That flies in the face of previous estimates that only about 2 million people lived in the entire Amazon basin."