### Key factors behind the decline of the (Western) Roman Empire

- **Chronic political instability**: Frequent coups, short-lived emperors, and civil wars fractured central authority and diverted resources from external defense.
- **Fiscal and economic strain**: Heavy taxation, currency debasement, inflation, widening inequality, and a shrinking taxable base undermined state capacity.
- **Military challenges**: Recruitment shortfalls, rising costs, reliance on foederati (barbarian allies) with mixed loyalty, and defeats like Adrianople (378) eroded security.
- **Overexpansion and logistics**: Maintaining vast frontiers and infrastructure exceeded the empire’s administrative and financial reach.
- **External pressures and migrations**: The Huns’ westward push displaced Goths, Vandals, and others into Roman territory, culminating in major incursions and sacks (410, 455).
- **Administrative fragmentation**: Division of the empire and bureaucratic complexity hampered coordinated responses, especially in the resource-poorer West.
- **Demographic and epidemiological shocks**: Plagues and population decline reduced manpower and economic productivity.
- **Social transformation**: Elite wealth concentrated in estates, localism grew, and urban life contracted, weakening state cohesion and revenue.
- **Strategic shift to the East**: The wealthier Eastern Empire (Byzantium) absorbed resources and survived, while the Western Empire lacked comparable resilience.

In sum, the Western Empire fell through the interaction of internal weakness and external shocks; the Eastern Empire endured until 1453, highlighting regional differences in resilience.