Okay so in North America, several native American tribes (for instance the Apaches) acquired horses and became extremely good horsemen. The benefits of cavalry on the great plains are somewhat obvious, but what if the Aztecs somehow managed to fend off the Spaniards? Would they have any real incentive to adopt horses? Mesoamerica was far more densely populated than North America, so I suspect that using horses as beasts of burden wouldn't be very attractive due to cheaper and easier-to-source human labour. The climate also seems sub-par for horses. So would there be any use for them at all to the Aztecs? If so, how would their culture be impacted?