Archaeologists, who study objects left by ancient people, have found that people have lived along the Nile for a very long time. The fertile flood plains of the Nile allowed people to begin farming. By the 10th millennium BC, the people in Egypt had begun growing cereal grains like wheat and barley. Because they were farming, they stayed in one place, and because they were settled, their society became more complex. This was an important step in the history of human civilization.