How did the nile river affect life in Egypt?

Since the Nile river got flooded three months per year the farmers farmed their crops the exact moment after the flood was over, since the water left black soil behind (Kemet) which was extremely fertile.

When the flood came back they obviously could not farm something so they went to the city and helped construct pyramids basically the nile was the only thing that helped them have huge amounts of crops, which they could later trade because they had surplus.