For periods without a historic record, attempts have been made to categorize tool kits, pottery styles, and architectural forms into regional timelines.
Some ill-fated attempts to define time even attempted to count backwards through the genealogies of the Bible, establishing a series of dates which remain a cause of confusion.
Chances are, right now, you have a Gregorian calendar stuck to your wall.
This calendar, with the months January through December, is a business standard used in many places round the world to define the year: one which hearkens back to Christian and Roman Imperial precedents.
But what does it actually do and how much can it tell us?