Roman calendar
The year started on 1 March and had only 304 days or 10 months (March, April, May, June, Quintilis, Sextilis, September, October, November and December). These 304 days were followed by an unnamed 50-day winter period. The Roman king Numa Pompilius (c. 715-673 BC) introduced February and January (in that order) between December and March, increasing the length of the year to 354 or 355 days. In 450 BC, February was moved to its current position between January and March.