in order to establish
the antiquity of the many cultures which developed
in the past, archaeologists study the superposition
of layers that form over time and the material found
within such layers. The study of the contents of tombs,
particularly pottery artefacts, enables experts to identify
the culture to which the (interred individuals) belonged.

More at the “Museo Rafael Larco Herrera”, Lima, Peru
gallery at; http://www.pbase.com/keithcollicoat/lima