And just like Mesopotamia where we have the Tigris and Euphrates, we're going to have a river system that's going to be the heartbeat of Egyptian civilization and of course that is the Nile. Egypt is called the gift of the Nile for a reason. Now if we start with the very basics, the Nile runs about 4,100 miles and it actually flows from the south to the north. So it starts in what today would be Ethiopia, Tanzania, kind of the highlands of central eastern Africa and it runs its 4,000 mile journey into the Mediterranean Sea. But Egypt isn't going to be able to use all of that Nile because there are points in the Nile which are kind of impassable at that point. It's called the first cataract which is about 750 miles south of the Mediterranean Sea. And this cataract, which is basically jagged cliffs and boulders and rapids, is really going to form the starting point for Egyptian society.