Battle of the Catalaunian Plains
In the fourth and fifth centuries the Huns expanded and conquered both the Sarmatians and the Germanic tribes living between the Black Sea and the borders of the Roman Empire. From bases in modern-day Hungary, the Huns ruled the entire territory formerly ruled by the Sarmatians. Their various constituents flourished under Hunnish rule, fought for the Huns against a combination of Roman and Germanic troops, and departed after the Battle of the Catalaunian Plains (451), the death of Attila (453), and the appearance of the Bulgar ruling elements west of the Volga.