Cities again

Well, just what is a city? And was Tenochtitlan, with its 200,000 inhabitants, one? There are lists of criteria drawn up by various urbanologists, all based on European models. But all such lists are arbitrary. Is a place still a "city" if almost everybody is occupied, either directly or indirectly, in agricultural production? And I don't mean just by going to the supermarket. In Tenochtitlan even the tlatoani ("he who speaks," same original meaning as the latin "dictator") had his lands producing food. Right now I'm inclined to think of Tenochtitlan (where Mexico City is today) as both and simultaneously one of the world's largest cities of its time (possibly the very largest) and the largest agricultural village. This rumination has led me to explore the etymology of these terms, and I recommend to you a wonderful site for word-lovers, the Online Etymology Dictionary, created and maintained lovingly by Douglas Harper -- for free. City, urbs, civil, town, village and so on. Of course, what is more relevant in my work is what such concepts meant to Spaniards in 1519 and the following years. I'll get back to you on that. I'm getting closer to understanding something I think is important.