They figure out how to drain the swamps of the upper Nile in order to increase their farmland. They begin building dikes to control the water in a more powerful way. They begin new public work projects. So the Middle Kingdom is important, we're just not going to talk about it a lot right now. What we do know is in that 1640 BCE, we have a group of Asian nomads that are called Hyksos, who are going to invade using horse-drawn carriages. They also invaded the Indus and the Fertile Crescent, so these nomads are just cray-cray for power, and they're going to take over Egypt. This is called the second intermediate period, about 1640 BCE to about 1570 BCE, and at that point we're going to get the rise of the New Kingdom and a much more powerful system of pharaohs and civilization in general.