This period was the most difficult for the Nile River Valley Civilization. There was a lot of corruption and rebellion from those who disagreed with the leader's decisions. In addition to social disorder, there were also many environmental problems such as power struggles and crop failures. Civilization simply did not arise as before. The most disastrous catastrophe that occurred during the Middle Kingdom was when the Hyksos invaded the Nile. Initially, the Egyptians admired the military technology of the Hyksos. Soon, 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 Hyksos rebels were driven out of the Nile, a new king arose, and thus the final period of Nile Valley civilization was born: the New Kingdom. During the New Kingdom, pharaohs founded great empires. These empires were so large that they reached the Euphrates River. For this reason, Hatsheput, a female pharaoh, encouraged trade with Asia and some along the Red Sea coast of Africa. This helped Egypt prosper. Their most powerful pharaoh during the New Kingdom was Ramesses II. He helped the economy and made great conquests against the invaders. Unfortunately, after Ramesses II, Egyptian power slowly declined and invaders, such as the Assyrians and Persians, began to conquer the Nile River valley.