The Spanish were, as far as we can tell, dramatically more brutal.

Not at all [1][2][3]. Why do you think the surrounding tributary city-states allied with the Spanish? Though human sacrifice was common in Mesoamerica at the time, under the Aztecs it took place at an unprecedented scale.

I'm curious, though, about why you'd make such an implausible claim without backing it up with any evidence.

[1] https://www.sciencemag.org/news/2018/06/feeding-gods-hundred...

[2] https://www.history.com/news/aztec-human-sacrifice-religion

[3] https://www.ancient.eu/Aztec_Sacrifice/

Than the Aztecs who used human skulls as construction material?

You mean like https://www.atlasobscura.com/places/wamba-ossuary ?

Yes, by orders of magnitude. The Aztecs sacrificed thousands of people; the Spanish sacrificed millions.

> the Spanish sacrificed millions.

Source?

Why not trillions?

While it's true they killed a lot, like most empires 5 centuries ago, they weren't as bad as the others.

Hernan Cortes defeated the whole Aztek Empire with 600 men. How? Easy, he had multiple tribes helping him because almost everyone of them wanted the azteks gone. That means they waged war against natives and they won. It has nothing to do with sacrifices.

From a total population of around 45 million, around 95% of them died smallpox and other deadly viruses.

Cortes even married an indigenous woman and had children with her just as a lot of other conquistadores did. The Catholic Kings legalized and promoted mixed marriages almost 500 years before it was legal in the US. That's why from Argetina to Mexico you can find millions of natives, millions of mixed people and millions of europeans.

The Spanish would have been quickly squashed all the way to the sea were it not for essentially every other native group allying with them against the Aztecs because of the brutal treatment they suffered since the rise of the Aztecs.

Once the Spanish had a foothold, European diseases did most of the killing.

Hernan Cortes had around 600 men. They had no chance against an empire like the Aztec. Fortunately for him other tribes wanted to see the tyrannical Aztecs gone.

Some people think he arrived there with laser rifles and nuclear bombs to wipe out and entire empire.

The propaganda around this is strong I guess.