Some of those other rivers would just flood whenever the time would be. But every July when the snow would melt in the mountains of Central Eastern Africa and the rain would come, the Nile would flood basically from July to October. So this kind of repeating pattern of flood, plant, harvest, flood, plant, harvest became the heartbeat of Egyptian society. It was dependable. They were able to use the Nile River to sustain their lives. Now around 3200 BCE, this is about 2,000 years into the growth of these small villages, we begin to get some trade with Mesopotamia, which has already invented cuneiform and other awesome technologies, which is going to allow Egypt to grow a little bit quicker because of those trade routes. It's in around 2000 BCE, they're going to be able to figure out how to navigate that Nile River for transportational purposes.