The Aztecs were once very great

In reality, Mexico could claim to be as old a civilization as Rome or Italy, or older. Both had the first glimmers of Mayan and Zapotec civilization dateable, we know now, to the same time as the Greeks, early Romans and the Jewish Captivity in Babylon. The Olmecs, for example were older than that. Empires of scale could be documented in both places at roughly the same time as well. Both Mexico and Italy were also victims of successive waves of 'outside' populations that overtook and established themselves over the stretch of centuries. Established religious and state forces created great monuments, groups and foes in battle went to war with each other, children were educated and intricate systems of trade - even economies of scale - extended their culture's reach and promise.

The biggest difference of course is that we know so much more about the one compared with the other. But it looks as though it's not even the act of writing that separates them here. Of course the mesoamericans also wrote things down in their chosen ways, but that had to be painted or chiseled (or both) because long-term paper or it's storage, doesn't work in the tropics where the Olmec, Toltec, Zapotec, Mayan and Aztec thrived. It did work in the much more arid Mediterranean climate. And they had centuries to perfect the tech of paper production and storage where it still just didn't work in the tropics so well. Most of the codices that were kept, the Spanish burned, when they found them. A few dozen survive.

Tenochtitlan was probably larger than any European city, too, at the time, even Paris, which was then twice the size of London, Rome or Istanbul. So while there were artists and priests and cooks and guards and boat-rowers, managers, washers and farmers, scribes, concubines we know very little about them. For centuries. There are stories and official chronicles unearthed, painted on walls, there are records of relations of city-states all over Mexico, and so on, but the picture still remains very incomplete. Much of this is because the study of the history of the place is relatively new and has begun to be sought out systematically, only in the last few generations. And much of the area falls into and out of war through no fault of the people again and then the jungle grows back so quickly, again.

So as I admit to spending the last year focused on Venice and Europe all over and nothing on Mesoamerica, that's only because of the lack of resources available here, in the US. Nothing exceptional about that.

I will try to offer as clear a picture I can though with the sources that are available to me. It's embarrassing how little we can say about these people.

It's easier to try to show the small differences between city-states in Italy and those in Mexico. In both there were interests at odds with each other for territory and the proceeds that could be coaxed from those territories. But in Mexico they were not  external forces vying for control of territory before the Spaniards arrived. Those forces were all internal and the conflicts - if we are to trust our sources - had been going for decades if not centuries with periods of temporary truce and peaces that sometimes stretched longer. The Aztecs were the most recent to come to the central valley of Mexico but it was because of them that the valley had been as stable as it had been for generations. The previous couple centuries had seen the rise of the Aztecs here and by 1490, they had achieved a stable control over much of Central America, holding sway over millions of people. Through conquest and the forcing of submission by other cities. First they went north and then they went south. They would make alliances, extort concessions, renew alliances and demand prisoners which they would then, ritually slaughter.

One example was Tlaxcala, a city on the way to the coast. This place, not far away the Aztecs had not overcome but would fight now and then and take prisoners which they took home to ritually slaughter as this was basic to the state religion of propitiating the sun god.

Much of this is from the introduction to The Broken Spears: the Aztec account of the conquest of Mexico, translated, edited with an introduction by Miguel León-Portilla, expanded and with a postscript, Boston, Beacon Press, 2006.