Short answers, pulled from the story.
The Sumerian King List dates to the second millennium BC and divides history into dynastic regnal eras. This ancient document serves as one of the earliest known attempts to categorize time into named blocks for study.
A more widely discussed system emerged in the early 5th century AD called the Six Ages of the World. This framework counted every age as exactly one thousand years from Adam to the present.
Italian poet Petrarch lived between 1304 and 1374 and conceived the idea of a European Dark Age. He compared his own period to the Ancient or Classical world and saw his time as a rebirth after a dark intermediate phase.
Music history places the end of the period in the year 1750 with the death of J. S. Bach. The Baroque period was first designated as such in the 19th century and is generally considered to have begun around 1600 in all media.
John Lubbock partitioned the Stone Age into Palaeolithic, Mesolithic, and Neolithic periods in 1865. Archaeologists rely on changes in material culture and technology to periodize the distant prehistoric past.