As a 'Medieval Warm Period' prevailed in Western Europe during the tenth and eleventh centuries, the eastern Mediterranean region, from the Nile to the Oxus, was suffering from a series of climatic disasters which led to the decline of some of the most important civilisations and cultural centres of the time. This provocative study argues that many well-documented but apparently disparate events such as recurrent drought and famine in Egypt; mass migrations in the steppes of central Asia; and the decline in population in urban centres such as Baghdad and Constantinople are connected and...