For detailed information about how seriation works, see Seriation: A Step by Step Description.
Archaeologists use many different techniques to determine the age of a particular artifact, site, or part of a site.
Two broad categories of dating or chronometric techniques that archaeologists use are called relative and absolute dating.
Without those, the archaeologists were in the dark as to the age of various societies. The use of tree ring data to determine chronological dates, dendrochronology, was first developed in the American southwest by astronomer Andrew Ellicott Douglass.
In 1901, Douglass began investigating tree ring growth as an indicator of solar cycles.
Until the 20th century, with its multiple developments, only relative dates could be determined with any confidence.