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. It's pretty easy going from the south to the north because the river goes that way. But once they figure out sails, which Mesopotamia is going to invent, they're going to be able to navigate the river using the trade winds, which flow from the north to the south. And then eventually they're going to be able to trade with internal Africa as they look for supplies to build their most awesome pyramids.