The Romans didn't really have that much of a tech advantage vs. steppe riders like the Huns when it came to practical combat. They also had good horsemanship (l

The Romans didn't really have that much of a tech advantage vs. steppe riders like the Huns when it came to practical combat. They also had good horsemanship (learning to ride as toddlers) and the valuable ability to fire arrows from horseback. However, the Huns were kind of an abberation. Most of the migrations/invasions were Germanic forest dwellers. In addition, for the most part it didn't look like an invasion. Many of the tribes were allowed to settle in the empire in exchange for military service, and Germans gradually started occupying the upper echelons of the military caste. By this time, the Western Roman Empire's institutions were just kind of falling apart. The local elites had little incentive to do much about it, and were happy enough to work with the Germans once Odoacer ripped off the bandaid and deposed the last emperor. Italy was actually quite prosperous for the century after the fall, until the Eastern Roman Empire initiated its reconquest and set off a series of wars.