The fall of the Roman Empire was due to a complex combination of factors that spanned several centuries. Key causes include:

1. **Political Corruption**: Weak leadership and political instability, characterized by frequent changes in leadership and civil wars, undermined the authority of the state.

2. **Economic Decline**: Heavy taxation, reliance on slave labor, and inflation weakened the economy. Trade disruptions following invasions contributed to economic troubles.

3. **Military Problems**: As the empire expanded, maintaining a vast military became increasingly difficult. The reliance on mercenaries, who were often less loyal, further compromised military effectiveness.

4. **Barbarian Invasions**: Various groups, including the Visigoths, Vandals, and Huns, invaded Roman territories, leading to significant territorial losses and weakening the empire's borders.

5. **Social Issues**: A decline in civic pride and public morale, coupled with social inequality, contributed to internal decay. The reliance on slavery also stifled innovation and economic mobility.

6. **Administrative Overreach**: The sheer size of the empire made it difficult to govern effectively, leading to inefficiencies in administration and response to crises.

7. **Cultural Changes**: The spread of Christianity shifted focus away from traditional Roman values, contributing to a loss of unity and identity.

The culmination of these factors led to the eventual collapse of the Western Roman Empire in 476 AD, while the Eastern Roman Empire, known as the Byzantine Empire, continued to thrive for nearly another thousand years.
