The ancient city of Angkor — the most famous monument of which is the breathtaking ruined temple of Angkor Wat — might have collapsed due to valiant but ultimately failed efforts to battle drought, scientists find.
Why do societies collapse? Often they are overextended, consume too many resources for their hinterland network to supply or they aren't able to adapt to changes to the system. Angkor Wat, the largest urban complex of the pre-industrial world, collapsed primarily due to drought conditions and a changing ecology. Without sufficient water resources, the network collapsed. What other environment 'collapses' can you think of?
Via Seth Dixon