What makes Empires crumble?

Answered on Quora

As someone who reads a great deal of history across all fields I have identified several reasons. Narrowing it done to one factor usually oversimplifies the issue. Here they are in my opinion

• Economic mismanagement and devaluation of the currency - the Empire’s chief currency loses buying power over time eg. Western Roman Empire;
• Poor leadership - A persistent chain of corrupt, weak and ineffective leadership eg. the Ottoman and Western Roman Empires;
• The Rise of an outsider power that is more aggressive eg. The Arabs taking down the Byzantine Empire;
• A series of catastrophic wars that saps the will to rule of the Empire’s elite eg. British Empire post WWI and WWII;
• Greatly increased Cost of administration - eg. The European Colonial Empires in the latter part of the 20th century;
• Over extension of power leading to blow back eg. Rome following Trajan;
• Leadership struggles eg. Mongol Empire post Genghis Khan or Alexander the Great’s Empire following his death;
• Failure to innovate and maintain a high level of technological progress eg. Ottoman Empire from the 18th century onward;
• Growth of Nationalism and Liberalism in conquered territory eg. South American uprisings against Spain the 19th century;
• Radical climate change leading to famine or drought eg. thought to be the main cause of the fall of the Mayan Empire;
• Civil War eg. Struggles between power groups within an Empire eg. Various Chinese Dynasty battles;
• Defeat by a coalition of forces eg. Japan during WWII or Napoleon’s Empire;
• Revolutionary change eg. Portugal following the Flower Revolution;
• Disease and Demographic disturbance eg. Impact on the Aztecs and Incas as a a result of the Spanish influence;
• Loyalty to the center core disappears with time eg. Austro-Hungarian Empire;
• Rise of ideology that undermines the core value system of the Empire - eg. Communism in the Tsarist Empire or as some would argue Christianity in Rome.