When did people start celebrating New Year's?

Romans were the first to celebrate the new year on January 1 in 153 B.C. in Rome. The earliest recorded celebration of the new year is around 2000 B.C., in Mesopotamia. This took place at the time of the vernal equinox, which is equivalent to the current calendar's mid-March period.

Despite the introduction of the January new year in 153 B.C., it was not always widely observed, and the many still took part in the March new year celebrations that the Romans had previously instituted. This continued until the Julian decrees of 46 B.C., which instituted a different, more accurate, calendar and confirmed the January 1 date as official.