From Jordanes, "The History of the Goths"
LIV (277) The kings [of the Suavi], Hunimund and Alaric, fearing the destruction that had come upon the Sciri, next made war upon the Goths, relying upon the aid of the Sarmatians, who had come to them as auxiliaries with their kings Beuca and Babai. They summoned the last remnants of the Sciri, with Edica and Hunuulf, their chieftains, thinking they would fight the more desperately to avenge themselves.....
LV.....Now Theodoric had reached man's estate, for he was eighteen years of age and his boyhood was ended. So he summoned certain of his father's adherents and took to himself from the people his friends and retainers,--almost six thousand men. With these he crossed the Danube, without his father's knowledge, and marched against Babai, king of the Sarmatians, who had just won a victory over Camundus, a general of the Romans, and was ruling with insolent pride. Theodoric came upon him and slew him, and taking as booty his slaves and treasure, returned victorious to his father. Next he invaded the city of Singidunum, which the Sarmatians themselves had seized, and did not return it to the Romans, but reduced it to his own sway.