The concept of celebrating the new year was first conceived by the Mesopotamians around 2000 BC. Specifically, it was the Babylonians, and they celebrated it during the spring festival of Akitu. In fact, for much of history, the new year was celebrated sometime spring. A few places, however, celebrate it in winter.
January---
The Gregorian calendar has its New Year in January. Why? The reason for this is Rome. Basically, the Romans didn't like having months in the winter time at first. It was a monthless time. They had ten months, totaling 304 days, March through December. Then Romulus's successor, King Numa Pompilius added January and February around 713 BC (Numa is about as mythical as Romulus, so some say it was actually the Decemviri, a group of ten men appointed to write up the law book of Rome, that invented January and February around 450 BC).
Another story explaining why January is the New Year month says that during the Lusitanian War (155-139 BC), two of Rome's armies were slaughtered, so two emergency consuls were appointed to send aid. They were appointed so quickly, it happened two and a half months before usual, January 1 instead of March 15.
To be updated...
January---
The Gregorian calendar has its New Year in January. Why? The reason for this is Rome. Basically, the Romans didn't like having months in the winter time at first. It was a monthless time. They had ten months, totaling 304 days, March through December. Then Romulus's successor, King Numa Pompilius added January and February around 713 BC (Numa is about as mythical as Romulus, so some say it was actually the Decemviri, a group of ten men appointed to write up the law book of Rome, that invented January and February around 450 BC).
Another story explaining why January is the New Year month says that during the Lusitanian War (155-139 BC), two of Rome's armies were slaughtered, so two emergency consuls were appointed to send aid. They were appointed so quickly, it happened two and a half months before usual, January 1 instead of March 15.
To be updated...