Carlos Noreña, a scholar of ancient history at University of California-Berkeley. “The Romans didn't impose their dating system,” Noreña says. The most recent dating battle has been a semantic one over the rise of C. “This is a little bit silly for two reasons,” Noreña says.“In the Middle Ages and Antiquity, there were multiple eras jostling for recognition.”The key wasn't what Year One was, as much as getting everyone on the same page. “But because they were so powerful and influential, people picked up their calendar and dating system because it was convenient.”While these were the dominant systems, there was a hodge-podge of various cultures with different Year Ones. “One, they use the same year, so it's the same system.The first two parts—the month and date—have had a legion of originators, from Cro-Magnon astronomers marking phases of the moon on their eagle bones, to Mayan mystics tracking the movements of the stars from their forest canopies. Tests date the Earth to about 4.54 billion years old, but a whole lot of that time didn't really have anything of substance—to us humans, at least.The 365-and-change-day calendar we use is the result of scientific sweat, an attempt to bring us to a Verifiable Truth regarding how long it takes the Earth to complete one rotation around the sun. Starting a calendar 4.54 billion years ago doesn't make much intuitive sense.By the ninth century, parts of southern Europe began observing first day of the new year on March 25 to coincide with Annunciation Day (the church holiday nine months prior to Christmas celebrating the Angel Gabriel's revelation to the Virgin Mary that she was to be the mother of the Messiah). However, England did not adopt this change in the beginning of the new year until late in the twelfth century.Because the year began in March, records referring to the "first month" pertain to March; to the second month pertain to April, etc., so that "the 19th of the 12th month" would be February 19.In the Year of Man's Retrospective Knowledge, by Astronomical Calculation 5000. The calendar lasted until 1806, after which Napoleon Bonaparte brought back the Gregorian calendar.  In 2012, American electrochemical engineer Libb Thims, in the overtly atheistic manuscript Purpose?
It's a three-part system allowing those in various locations and points of time to distinguish when an event occurred or will occur. Spoilers: The planet's been around longer than any of us—or any of our ancient relatives—can remember.
Today, Americans are used to a calendar with a "year" based the earth's rotation around the sun, with "months" having no relationship to the cycles of the moon and New Years Day falling on January 1.
However, that system was not adopted in England and its colonies until 1752.
(in a Godless universe), began to employ the “printing era” dating system, dating the modern era to years before or after 1450 the year of the invention of the printing press, throughout, using the abbreviations BP (before printing) and PE (printing era) in place of BC/AD dating method.
 On , the printing era BP/PE dating system was introduced online, namely into the Empedocles article, and thereafter into about 100 other articles.