I’ve heard this sentiment expressed about the Aztecs before, so I’ll handle that part of the issue.
The idea that the Aztec (or rather Mexica/Triple Alliance) Empire was on the decline has appeared in several historical texts. However, in all cases it is on pretty shaky ground. Let’s begin with Conrad and Demarest’s ‘Religion and Empire: The Dynamics of Aztec and Inca Expansionism.’ This was one of the earlier texts to investigate ideology in the context of New World Empires. The argument, at least for the Aztecs, was that the need to acquire victims for sacrifice to the sun, Huitzilopochtli. To be clear, this idea had existed before. The first elements of it appeared in Alfonso Caso’s ‘People of the Sun’ and Miguel León-Portilla had also made similar comments. However, Conrad and Demarest were the first to really develop a comprehensive model. One of the consequences of this ideology was that the Mexica Empire was inherently unstable, and was ultimately doomed to collapse, ‘What ever the future of the Mesoamerican cultures might have been, it is clear that the era of the Triple Alliance was coming to a close.’
So what are the problems with this interpretation? The first is that it massively overemphasises the importance of religion and sacrificial captives for the Mexica state. The work of scholars such as Michael E. Smith and Frances Berdan have show that Mexica expansion was driven mainly by issues of economic and political security. Ross Hassig noted that religion was rarely used to justify warfare in Mesoamerica. Most often, trade disputes were the cause of conflict, not religious imperatives. Furthermore, Conrad and Demarest base much of their claims of ‘Aztec’ disillusionment on Diego Durán’s account of the Mexica’s history immediately prior to the Spanish Conquest. Two problems with this. First, the chronicle, at this point, is heavily focused on Motecuhzoma’s personal existential drama, and therefore is not necessarily representative of what the whole structure was feeling. Second, it was written decades after the Conquest, and it is likely that Durán’s sources, or Durán himself, took some artistic liberties with the tale. The Conquistadores that actually met Motecuhzoma, namely Cortés and Bernal Díaz, don’t give us any indication that Mexica society was undergoing any real crisis. At least until they caused one.
Of course, it isn’t just this source. There are a few other comments made by historians that may lead a reader to believe that the Mexica were in decline. One example comes from Davíd Carrasco who suggested that the Mexica were suffering from financial problems. I.e. they were bankrupt. He wasn’t the only historian to make this claim. Nigel Davies made similar statements about the Mexica’s financial state (although he did not believe that the Empire’s state was terminal), as did Frances Berdan and Patricia Anawalt. These last two specifically attributed this lack of funds to Ahuitzotl’s magnificent dedication of the Templo Mayor. Two problems. The first is that we know so little of the Mexica’s finance system that drawing any conclusions about the state of their coffers is pointless. Take the aforementioned dedication of the Templo Mayor for an example. This occurred in 1487, 32 years before Cortés arrived in Mexico. The Mexica had plenty of time to replenish their stash, and they showed no signs of weakening in the subsequent decades. This brings me to the second problem, which is again that the Conquistadores Cortés and Díaz did not report, or notice, any solid evidence that the Mexica were strapped for cash.
If the idea that the Mexica were in terminal decline is based on such shaky evidence, why do people, including scholars, make the claim? I feel that there are two reasons. The first, is because of the Roman Empire. The Roman Empire, famously, went through a long period of decline before finally collapsing, at least in the West. Of course, the reality was a bit more complicated, but this is how people learn it when they are children. Therefore, the Roman Empire becomes a model for how Empire’s are supposed to go. Since the Roman Empire declined before it fell, so too must the Aztec Empire. The second reason is guilt. If the Aztec Empire was on the way out anyway, then the actions of the Conquistadores does not seem so bad. If this were the case, then they just happened to be in the right place at the right time, and it was really the Mexica’s fault they weren’t good enough at empiring. This reasoning is, of course, ridiculous, but it makes people feel a little better about what happened.
Sources:
Berdan, Frances F. and Anawalt, Patricia Rieff: - The Codex Mendoza Volume II: Description of the Codex, (Berkeley: University of California Press, 1992)
Berdan, Frances F., Blanton, Richard E., Boone, Elizabeth Hill, Hodge, Mary G., Smith, Michael E., and Umberger, Emily: - Aztec Imperial Strategies, (Washington D.C.: Dumbarton Oaks, 1996)
Conrad, Geoffrey W., and Demarest, Arthur A.: - Religion and Empire: The Dynamics of Aztec and Inca Expansionism, (New York: Cambridge University Press, 1984)
Cortés, Hernan: - Letters from Mexico, tr. Anthony Pagden, (New Haven: Yale University Press, 1986)
Carrasco, Davíd: - Quetzalcoatl and the Irony of Empire: Myths and Prophecies in the Aztec Tradition, (Boulder: University Press of Colorado, 2000)
Davies, Nigel:
Díaz, Bernal: - The Conquest of New Spain, tr. J.M. Cohen, (London: Penguin Books, 1963)
Durán, Diego: - History of the Indies of New Spain, tr. Doris Heyden, (Norman: University of Oklahoma Press, 1994)
Hassig, Ross: - Aztec Warfare: Imperial Expansion and Political Control, (Norman: University of Oklahoma Press, 1998)