Answer :
In general, it would be "civil war" and "foreign invasion" that most contribute to the fall of empires, since natural disasters are relatively rare in the sense and economic prosperity helps empires thrive.
Answer: Civil War, foreign invasion and natural disasters.
When an empire falls, it is usually due to a combination of factors that damaged its stability. These are some of the most common ones. Civil war can often fracture an empire from the inside. Foreign invasion is also a common reason for empires to decline. Natural disasters, although uncommon, can also pressure the empire to the point of a crisis and lead to its fall.