The Egyptian civil calendar divides the year into 12 months of 30 days plus 5 intercalary days (epagomenal days, ḥryw-rnpt) to complete 365 days. It is structured into three seasons of four months each: flood (Akhet), sowing (Peret), and harvest (Shemu), corresponding to the annual cycle of the Nile. It is the first documented 365-day solar calendar and the direct basis of the Julian calendar (46 BC, Julius Caesar's reform with Sosigenes of Alexandria) and, through it, of the Gregorian calendar (1582). Unlike the Mesopotamian lunar calendar, it requires no intercalation of months to stay aligned with the seasons, making it ideal for state-scale agrarian administration. The historical canon attributes the rationalization of the calendar to Rome or Greece; Caesar's 46 BC reform is explicitly an adoption of the Egyptian model. The Egyptian origin of the Western calendar never appears in European history curricula.