So the Upper Nile is actually south of the Lower Nile. Of the Lower Nile. And once again, that's because the Upper Nile is upriver. It's also flowing from higher elevations to lower elevations. So as you go south, you get to higher and higher elevations. Now, the reason why the river is so important, we've studied this multiple times, rivers are a source of fresh water. When they flood, they make the surrounding soil fertile.