Ancient roman dating calendars
They evolved over the centuries, but month names changed little until now.The unified Achaemenid Empire required a distinctive Iranian calendar, and one was devised in Egyptian tradition, with 12 months of 30 days, each dedicated to a yazata (Eyzad), and four divisions resembling the Semitic week.
A ceramic artefact from Bulgaria, known as the Slatino furnace model, has been pronounced by local archeologists and media to be the oldest known calendar representation, a claim not endorsed in mainstream views.
A 13th month was added every six years to keep the calendar synchronized with the seasons.
The first calendars based on Zoroastrian cosmology appeared in the later Achaemenid period (650 to 330 BCE).
Old Persian inscriptions and tablets indicate that early Iranians used a 360-day calendar based on the solar observation directly and modified for their beliefs. The months had two or three divisions depending on the phase of the moon.
Twelve months of 30 days were named for festivals or activities of the pastoral year.The natural units for timekeeping used by most historical societies are the day, the solar year and the lunation.