He was King of the Huns from Asia who defeated the Roman Emperor Theodosius and entered Gaul – but was defeated in A.D. 451 near Châlons-sur-Marne. Who was he?

He was King of the Huns from Asia who defeated the Roman Emperor Theodosius and entered Gaul – but was defeated in A.D. 451 near Châlons-sur-Marne. Who was he?