This period was the most difficult in the civilization of the Nile Valley. There was a lot of corruption and rebellion from those who disagreed with the leader's decisions. Besides social disruption, there were also many environmental problems such as power struggles and crop failures. Civilization simply did not develop as it had been. The most disastrous disaster to hit the Middle Kingdom occurred when the Hyksos invaded the Nile. At first, the Egyptians admired the military technology available to the Hyksos. Very quickly, the Egyptians mastered this technology and the Hyksos were impressed. This caused many Hyksos to adopt Egyptian culture, language and even names. About 100 years later, the rebellious Hyksos were driven from the Nile, a new king appeared, just like the last period of Nile Valley civilization: the New Kingdom. During the New Kingdom, pharaohs built great empires. These empires were so large that they reached as far as the Euphrates River. For this reason, Hatsheput, a female pharaoh, encouraged trade with Asia and some along the African Red Sea coast. This helped Egypt prosper. Their most powerful pharaoh in the New Kingdom was Ramesses II. He helped the economy and made great conquests from the invaders. Unfortunately, after Ramesses II, Egyptian power slowly declined and invaders, such as the Assyrians and Persians, began to conquer the Nile Valley..