Why did people come up with the calendar?

When ancient people began to cultivate fields, grow bread, they noticed that the time of sowing and harvesting falls on the same period.

The ancient Egyptians noted that the Nile floods every 12 full moons (moons). The spill was detrimental to the already planted seedlings, but brought fertile soil in the form of silt. They learned to predict the next flood by counting 12 months from the moons. It was also noted that at the same time as the spill began, a bright star (Sirius) lit up in the sky before sunrise. We decided to count the days between the stars, it turned out that there are 365. This is how the first attempt to determine the number of days in a year took place. Then the Egyptians divided 365 days into 12 months of 30 days, and at the end of the year they added another 5 days. This is how the first calendar appeared.