30 ARCHAEOLOGY • March/April 2018
rather in a constellation of cities and towns linked by a shared
religion and the culture that went along with it. Compared to
the riches flaunted by the priests, Moche commoners didn’t
enjoy many luxuries. But they trusted that their leaders would
keep them safe by staying in constant contact with the gods.
And it seemed to work—until the weather changed for good.
Beginning around a.d. 550 , a series of particularly harsh
El Niños struck the north coast. Excavations in Moche cities
of that time have revealed layers of mud and sand, indicating
rapid shifts between extreme wet and dry weather. In one
Moche city, Vogel says, sacrificial victims were left lying facing
down in the mud, an unusual practice that hints at the religious
authorities’ desperation. The deluge needed to create that
amount of mud in the desert would have been devastating,
Vogel says. “Nothing is built to handle it. This area is usually
so dry that folks didn’t even bother to fire their bricks. They’re
just sun-dried adobe. You subject that to a torrent of water
coming down from the valley, and it’s gone. It’s just a pile of
mud.” Meanwhile, the dry periods in between storms became
longer and longer, finally extending into a devastating drought
recorded in ice cores from Andean glaciers. Crops failed and
sand dunes encroached upon Moche cities. “It seems like there
are some serious disturbances occurring,” says Koons.
The Moche began to falter. Cities turned away from tradi-
tional Moche rituals and architecture, and new ceramic styles
sprang up, Koons says. By the time El Purgatorio was built,
around a.d. 700 , after about 150 years of climate chaos, the
Moche had definitively lost their grip within the southern
part of their territory, which had once extended to just north
of the Casma Valley. “If you have a government that is built on
claiming to have control over what seem to be supernatural
events, climate change can lead to real political instability,”who studies the Moche. “They’re telling you, ‘Follow us, and
everything will be great.’” The Moche did conquer some areas.
But up and down the north coast of Peru, people found this
religion compelling—or protective—enough to convert by
choice to the Moche way of life. According to Quilter, that
resulted not in a centrally administered, unified state, but
A simple adobe frieze decorates a raised platform that was
constructed next to one of El Purgatorio’s public plazas.The Casma people did not invest
time in making elaborate pottery like
their predecessors the Moche, instead
preferring to create ceramics with
modest decorations, such as these.