Astronomy is what created our and every civilizations' calendars. Days, months, years, all are tied to astronomical events.
I'm going to have to go with "Astronomy".
BY watching the sky, the priests learned about Astronomy and developed a 365-day calendar
Xishan Wang has written: 'Xiao'an xin fa' -- subject(s): Astronomy, Astronomy, Chinese, Calendar, Chinese, Chinese Astronomy, Chinese Calendar, Early works to 1800
The days of the week are named after the seven planets of classical astronomy. However, their order in the calendar differs depending on the society or tradition. Link of Wikipedia entry can be found below.
The Anasazi used astronomy *Your welcome*
the purpose was to keep track of holidays farming and astronomy
From the Google calendar's Settings there is a link to Delete your calendar.
They were really good at astronomy, pyramid-building, and calendar-making.
A two calendar system
The invention that the Babylonians were known for was the accurate calendar, astronomy, and mathematics.
See related link for 1943 calendar.
Click on the link below for the calendar .