The first inundation according to the calendar was observed in Egypt's first capital, Memphis, at the same time as the heliacal rising of Sirius. The Egyptian year was divided into the three seasons of akhet (Inundation), peret (Growth-Winter) and shemu (Harvest-Summer).The heliacal rising of Sothis returned to the same point in the calendar every 1,460 years (a period called the Sothic cycle).or much of Egyptian history, the months were not referred to by individual names, but were rather numbered within the three seasons. As early as the Middle Kingdom, however, each month had its own name.