Clues to Climate Change In Egypt's Past

http://www.cnn.com/2005/TECH/science/04/08/earth.past.future/index.html?section=cnn_latest
"Harvey Weiss, professor of archaeology at Yale University, says climate change was a fact of life for earlier civilizations. From pharaohs to the medieval Vikings, swift and sometimes violent changes in weather patterns sparked mass migrations and technological innovations like irrigation."
The article goes on to discuss past climate change in general terms.