Collapse of civilization

 While there is no single accepted theory for why collapses happen, historians, anthropologists and others have proposed various explanations, including:

                                                      Full list

• INEQUALITY AND OLIGARCHY
• ENVIRONMENTAL DEGRADATION
• CLIMATIC CHANGE
• COMPLEXITY
• EXTERNAL SHOCKS
• “four horsemen”: war, natural disasters, famine and plagues
• RANDOMNESS/BAD LUCK
• “Red Queen Effect”: if species are constantly fighting for survival in a changing environment with numerous competitors, extinction is a consistent possibility.

Don’t have a conclusive explanation as to why civilisations collapse. What we do know is this: the factors highlighted above can all contribute.

Reference: Are we on the road to civilisation collapse?