archaeologist arthur demarest. throughout the course of human history, societies have bece ever more complex. political systems have developed -- some successfully, expanding and growing, while othersecline and disintegrate. what are the differences between these societies ? why do some political systems succeed and others fail ? that's one of the central questions that we have to address in archaeology. keach: the aztec political system was one of the great success stories of all pre-industrial societies. they created a rich and powerful empire that dominated millions of people. they lived in the valley of mexico in the area that is now mexico city. before coming to power, the aztecs were just one of a number of small city-states located in the region. archaeologist william sanders. between 1200 a.d. and 1428, the area was occupied by 40 competing states. occasionally, one of these states would conquer some of the others and form a small empire for one or two generations. but then it would collapse again. in 1428,