Why did people in the ancient kingdoms begin to draw up a calendar?

The reason for the compilation of the calendar in the ancient kingdoms is very simple and lies on the surface. And the thing is that their most important occupation was agriculture. They grew many crops. Many crops require specific care, and some depend on the time of year, specific temperatures, and so on. So, in order to know when to plant and harvest the crops, calendars were drawn up, according to which the ancient people were guided and calculated the exact days, what and when should ripen. It was practical and convenient.