What led to the political and economic decline of Europe during the Early Middle Ages?

The political and economic decline of Europe during the Early Middle Ages can be attributed to the collapse of the Roman Empire. The disintegration of Roman authority led to a power vacuum, resulting in fragmented territories and a decline in centralized governance. This period, often referred to as the "Dark Ages," saw reduced urbanization, a drop in trade, and a shift away from the advanced infrastructures that the Romans had established. As safety and stability diminished, many people turned to local lords for protection, further contributing to a feudal system.

The other options reflect developments that are often misinterpreted in context. For instance, the flourishing of trade routes across Europe occurred much later and resulted from revitalization that followed the Early Middle Ages, not from that era's conditions. Increased territorial stability also does not characterize this time, as fragmentation and conflict were prevalent. The establishment of city-states was a later phenomenon that contributed to revival, but during the Early Middle Ages, many cities declined or disappeared entirely. Therefore, the collapse of the Roman Empire is pivotal in understanding the subsequent challenges Europe faced during this formative time.