That is a blatantly clickbait-and-switch post title. Anyone expecting to read about the origins of romantic outings involving two people will have to look elsewhere. What this post is about is how the idea of assigning consecutive numbers to the years originated.
We now routinely assign a numbered year to events in recorded history, so that I can write that Bishop Ussher’s year of the creation of the Earth was 4004 BCE or that the American revolution was in 1776 CE. This sequential numbering of the years enables us to immediately fix an event in relation to other events. The system seems so natural that one feels that it must have always been in place and did not have to be invented at all, let alone have a definite beginning. But classicist Paul J. Kosmin says that there was a time when this system of numbered years did not exist and that events were placed in a historical sequence using various circumlocutions that had only local validity.