I assume your talking about the HUNS... When the empire split in two the east had more gold and more resources and the dying west had to suffer all the barbarian attacks like the huns... The East quite simply was more prepared and had more walls and guards to defend their border also the Eastern Empire had the river danube north of them which helped deflect the Hunnic invasions and other barbarian invasion more west...
It’s C. Time study analysis hope it works for you
Sometime between 30 and 33 A.D
Crosby's focus on smallpox changed his and later historians' views toward ecological and. ... Disease, specifically smallpox and malaria, was the main reason Europeans conquered indigenous peoples. Horses and weapons provided advantages, but infectious disease did the most damage.