The Nile River is life itself for Egypt, both now and in ancient times. Because the annual rainfall in Egypt is an average of 2 millimeters (0.07 inches), the River Nile provides all the water needed for humans, animals, and plants to live. The annual flooding is a crucial aspect of Egyptian life, providing fertile soil for agriculture and sustaining the population. The flooding season coincides with the rising star Sirius and is a significant event in the Egyptian calendar.