One of the regions of the planet that benefited from the end of the ice age was Mesopotamia. In fact, this area of the planet is thought to be the starting point of today’s civilization; since Sumerian influence has been determined in the Egyptian, Hindu and Chinese civilizations.
The Egyptians used a calendar based on the 365-day annual cycle, probably from the fourth millennium BC. The Nile began its annual flood at the beginning of the year, at the time when the star Sirius, after having been invisible below the horizon, could be seen again shortly before the sun rose. Over time they observed that this phenomenon was delayed, and hence it was deduced that the length of the year was actually 365.24 days. This difference was corrected in 238 BC. when a day was added every four years, to make up for this delay. Herodotus, says in the Histories of him: “the Egyptians were the first of all the men who discovered the year, and they said that they found it from the stars”.