[29athrowaway]

The "aztecs" (Mexica) are not a good example. The Fall of Tenochtitlan was facilitated by an alliance between the Spanish Empire and Tlaxcala.

The Tahuantinsuyu (Inca) had a civil war of succession followed by a purge of the nobility after the monarch died Huayna Capac of smallpox.

So not even in those cases they faced a unified front.

And the innovations you mention are not enough. On one side you have no navigation technology (map making, compass, etc), no animal traction.

[polartx]

That is correct, and I feel like it supports my point..in both of those examples the incumbent empire was weakened by infighting—-a non unified front. I’m not as steeped on the Aztecs as I am the Incas, but Pizarro and Diego de Amargo arrived as conquerors in a company whose singular purpose was conquest. They were encircled and outnumbered 500 to 1 in what was effectively a kill box. Technology and horses gave them the upper hand, but the domino which instituted the downfall of the Incan empire is that the emperor himself was present _inside_ the killbox. Pride goeth before the fall. Which allowed Pizarro to charge through his soldiers and literally seize him from his royal litter…I don’t think this exception disproves that a unified front with defensive emplacements could have withstood a few hundred horse borne conquerors.