Chinese calendar dating
The Julian calendar was no longer dependent on the observation of the new moon but simply followed an algorithm of introducing a leap day every four years.
This created a dissociation of the calendar month from the lunation.
During the Warring States period (~475-220 BC), the primitive lunisolar calendars were established under the Zhou Dynasty, known as the six ancient calendars (simplified Chinese: ).
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.
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).