About 4,200 years ago a series of disasters struck cities and civilizations throughout the Middle East.

In Egypt the central government collapsed. The same state that had built the great pyramids, and kept pharaoh as the supreme authority, could no longer keep the country united. This ushered in an era of powerful provincial leaders (known as nomarchs) and rival claimants to the Egyptian throne.

A similar scenario happened in Mesopotamia where the Akkadian Empire, an entity whose power stretched from the Persian Gulf to the Mediterranean, also went under. This led to local rulers stepping in and taking up power.

There is also evidence of social upheaval in the Levant. The city of Khirbet ez-Zeiraqoun in northern Jordan, whose inhabitants burrowed out hundreds of meters of water tunnels into the ground, was abandoned.

Climate change is believed to be a major reason for this upheaval. Research in the Middle East suggests that the environment became increasingly arid – making it difficult to support the intensive farming that is required to feed large cities....