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Hello, according to legend, the origins of the Aztec Empire lie on a mythical island called Astlan, a place of the white herons in the North of Mexico.

From there, this nomadic group of Mesoamericans are said to have undertaken a pilgrimage in the 13th century south to the fertile valleys of Central America.

In the space of just 200 years, they formed what's been called the largest and arguably the most ruthless pre-Hispanic empire in North America, which at its zenith was ruled over approximately 500 small towns comprising by the 16th century some 10 million people.

Was it military might and intimidation alone that helped the Aztecs extend their power? What part did their complex belief system play in their imperial reach?

That use of human sacrifice has been well documented, but how widespread actually was it? How easily were the Spanish conquistadors able to Christianize this empire? And what legacy did the Aztecs leave behind that lives on in our world today?

With me to discuss the Aztec Empire, Alan Knight, professor of the history of Latin America at Oxford University and author of Mexico from the beginning to the Spanish conquest, Adrian Locke, co-curator of the Aztecs exhibition, current at the Royal Academy of Arts, and Elizabeth Graham, senior lecturer in Mesoamerican archaeology at University College London.

Alan Knight, what exactly were the Aztecs and where did they come from?

The Aztecs gained a lot of different names, which makes it complicated, but if we stick to Aztecs for the moment, they were a migrant people who came down from Northern Mexico probably around the 12th or 13th century.

Part of a much greater movement of people, which traditionally came from North to South, from the big open rather arid regions of Northern Mexico, and came to settle in Central Mexico, particularly in the Valley of Mexico itself, which is a well-watered fertile basin,

which had been the cradle of major civilizations in the past with both Teotihuacan and Tula.

And so the Aztecs were sort of relative late comers who then settled, gradually developed and sort of grafted their loosely barbarian stock onto existing civilizations, and then rather rapidly in late in the day, developed their own city state and eventually an empire, which as you said then stretched over large areas of Central and parts of Southern Mexico as well.

You used the word barbarians to talk about the Aztecs when they came to the Central American lush lowlands there, and they met older civilizations.

What were these older civilizations like and based on, and how did that make the Aztecs seem barbarians by contrast?

There had been at least two major empires in the region of Central Mexico going back to the first millennium after Christ with Teotihuacan, a major city in the northern part of the Valley of Mexico.

And then later between about 91100 or somewhat less large and integrated empires centered on the city of Tula, a little to the northwest.

So there was a tradition in this region of creating large cities which became the hub of reasonably broad extended empires.

The Aztecs coming in as rather small, weak migrant population eventually working their way up then began to intermarry and appropriate some of the legend, the ideas and the legitimacy of those previous civilizations, particularly the Toltecs of Tula, who the Aztecs looked to as their kind of mentors and models as they embarked on their own civilization and their own sort of imperialistic efforts.

Is there any sense at all that the civilisations and the Aztecs met had drifted over from Europe, had any connection with the Tauhaidol raft that came over Egypt to Central Mexico?

I would say none whatsoever. This is a theory that recurrently gets produced and includes sort of gems as Lord Kingsborough going bankrupt trying to show that the lost ten tribes of Israel came over and settled in Central America.

The Tauhaidol may have shown you could cross the Atlantic on an Egyptian raft but that doesn't mean the Egyptians did and the fact there are a few similarities in building style, use of pyramids, none of that suggests any evidence.

And more recently you also have genetic evidence which I think pretty much shows that the origins of the American peoples really come from East Asia.

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