This video explains Attila the Hun, who was a barbarian leader that invaded Europe during the 400’s AD, likely originating in Mongolia.  The Roman Empire described him as being “the scourge of god,” where he and his hordes of nomadic troops pushed large amounts of Germanic people deeper into Europe due to their fleeing his attacks, and the Huns also eventually attacked Constantinople and Italy.  By the time Attila died, the “Hunnic Empire” was even larger than the Roman Empire, occurring at the time when the western Roman Empire collapsed.