Around 50,000 years ago, ancient Egyptians transitioned from nomadic life to agriculture, settling along the banks of the Nile River. Their agricultural harvests were closely related to whether the Nile flooded. Through long-term observations, the ancient Egyptians found that the timing of the Nile's floods was regular. They recorded this time on bamboo poles each time, and from this they learned that the time between two floods was approximately 365 days. At the same time, they discovered that when the initial surge of the Nile reached the area near present-day Cairo, it coincided with the time when the sun and Sirius rose together above the horizon.
　　Therefore, the ancient Egyptians set this day as the beginning of the year. This is the origin of the "New Year's Day".