The end of the Old Kingdom, around 2100 BC, seems to have been caused by a major climate change. In Egypt, there was a terrible drought – the Nile failed to flood, or flooded less than usual, so there wasn’t enough water to grow enough food. Then food shortages led to rebellions among the nomarchs – the governors and rich people. They thought that the Pharaohs weren’t doing a good job.
During the Old Kingdom, the Pharaohs had gotten more and more dependent on the government officials under them. Now these government officials grabbed power. Some of the organization of the country collapsed, and everybody was poorer. Nobody could afford to build pyramids or fancy palaces anymore. Egyptian writers make it sound really awful to live through. Rich men and women were working in the fields. People were killing their parents, brothers were fighting, and tombs were destroyed. Probably a crisis that was hard on rich people was much harder for ordinary people.
This terrible drought in Egypt also affected West Asia, where the Akkadian Empire fell apart, and Central Asia, where it may have forced the Indo-Europeans to begin a great migration, and India, where the Harappan civilization collapsed.
Eyewitness: Ancient Egypt, by George Hart. Easy reading.
The Oxford History of Ancient Egypt, by Ian Shaw (2002).
History of Ancient Egypt: An Introduction, by Erik Hornung (1999). A college textbook. On the conservative side – not much on new developments.
Ancient Near Eastern History and Culture, by William H. Stiebing (2002). Expensive for a paperback, but brief and very up to date. And yes, it includes Egypt in the Near East.