Final answer:
The Huns, a group of warriors from the central Asian steppes, came the greatest distance to the former Roman Empire. The Byzantine Empire was one of the areas of the empire that was not threatened by invasion.
Step-by-step explanation:
The group of invaders that came the greatest distance to the former Roman Empire were the Huns. The Huns were warriors from the central Asian steppes and were known for their expertise in horse-riding and ferociousness in battle.
There were some areas of the empire that were not threatened by invasion. One example is the Byzantine Empire, which was able to withstand invasions due to its strong military defenses and geographical location.