Aztec Empire

The Mexica told their own origin as a migration: a people sent from Aztlan by Huitzilopochtli, wandering until they saw the promised sign of an eagle on a cactus on an island in the lake, where they founded Tenochtitlan in 1325. A century later, after helping to overthrow the Tepanec overlords, they formed with Texcoco and Tlacopan the alliance that became the empire.

Their capital was built as a diagram. At its centre the Templo Mayor rose as a double pyramid carrying two shrines side by side, one to Tlaloc, who brought the rain, and one to Huitzilopochtli, who was the sun and the war god, so that the agricultural and the martial halves of the world stood on one platform. Eduardo Matos Moctezuma's excavations from 1978 found seven superimposed constructions, each enlargement burying the last, and more than a hundred deposited offerings containing objects brought from every corner of the tributary empire, which made the temple a map of what the empire had absorbed.

The system that governed it was the calendar: a 260 day ritual count and a 365 day year interlocking in a round of 52 years. At the end of each round every fire in the world was extinguished and a new one kindled on a hilltop at midnight, and Miguel Leon-Portilla's study of Nahua thought shows the philosophers of this culture arguing, in the poetry they called flower and song, about whether anything on earth is true or lasting.

Human sacrifice is the fact everyone knows about this empire and the hardest one to write about accurately. Within Mexica understanding the cosmos was not stable: four previous suns had ended, and the fifth was sustained only because the gods had thrown themselves into a fire at Teotihuacan, a debt that human offerings repaid. Captives taken in war, including in the arranged flower wars fought against neighbouring states for that purpose, were the ordinary victims, and the archaeological record at the Templo Mayor, including the skull rack excavated at its foot, confirms that the practice was real and organised.

The scale is another matter. The figure of eighty thousand at the temple dedication of 1487, repeated for centuries, is arithmetically impossible, and nearly all the narrative evidence comes through Spanish channels: Sahagun's Florentine Codex compiled from Nahua informants a generation after the conquest, Duran, and the accounts of conquerors who had every reason to describe what they had overthrown as monstrous. A separate argument ran through the 1970s over whether sacrifice served a nutritional function, and the ecological case was answered in detail and is not now generally accepted.

Tenochtitlan fell in 1521 and the temples came down, but Nahua religious life continued under Catholic forms, in the cult of saints, in the calendar of village fiestas and in the shrine at Tepeyac, and the excavated Templo Mayor now stands open in the middle of Mexico City.