Meroe, the main city of the middle Nile kingdom of Kush, is impressive in its longevity (ca. 1,069 B.C.– 350 A.D.), scale (approx. 1,000 miles of the Nile valley), and cultural achievements (e.g. pyramids), but both its origins and demise are shrouded in relative obscurity.
The presence of a victory stele, or column, erected by King Ezana provides direct evidence of a seizure of Meroe by the Aksumites around 330 A.D. Therein lies the proximate cause of the collapse of Meroe, and the disappearance of Meroitic language around the same time points to the significance of the Aksumite invasion; however, historians point to some other factors that likely contributed to the demise.
Overuse of the land could have led to desertification. Meroe's iron industry required large amounts of wood, which led to deforestation. Deforestation leads to more runoff, with less moisture being absorbed by the soil. Meanwhile, overgrazing could have contributed to mineral depletion and soil erosion. In combination, these factors would have undermined agricultural productivity.
Aside from the Aksumites, there were nomadic tribes that launched periodic incursions into Kush territories. Aside from direct losses from skirmishes and battles, there was likely competition over resources with the nomadic groups and the disruption of important trade networks. Within the context of agricultural decline, this competition could have had dramatically detrimental effects on Kush and Meroe. The Aksumite invasion would, therefore, have been the final blow to a declining civilization. By the 400s A.D., Meroe was abandoned. Strangely, there is also some evidence that on the eve of collapse, the Kush kingdom was doing quite well. Archaeological research continues at Meroe and we will likely have some more certain answers in the years to come.