Another collapse by changing environment is (likely) that of the Maya civilization: https://en.wikipedia.org/wiki/Classic_Maya_collapse#Drought_theory https://

Another collapse by changing environment is (likely) that of the Maya civilization: https://en.wikipedia.org/wiki/Classic_Maya_collapse#Drought_theory https://en.wikipedia.org/wiki/Classic_Maya_collapse#Drought_... A civilizational collapse is rarely caused by a single event, but instead by multiple events - each which would be survivable on their own - causing a complete breakdown in the system. A society can survive a drought, a war, a plague, a famine, but all four at once might just be too much. It's not for want of a nail that a kingdom is lost, but because of all accumulated failures and breakdowns which led to the point where loss of a single nail was just that one failure too much. Death by drowning in a million raindrops.