Jordanes reported that during the reign of the Emperor Domitian the Goths broke a truce they had with the Roman emperors (XIII 76). After several victories, including a successful defence against a Roman counterattack, Jordanes claimed that the Goths likened their leaders to demigods or "Ansis" (XIII 78). According to Jordanes, Ostrogotha was part of the Amal family, whose genealogy he recited, making him an ancestor of Ermanaric and Theodoric the Great (XIV 79).
- Ablabius the historian relates that in Scythia, where we have said that they were dwelling above an arm of the Pontic Sea, part of them who held the eastern region and whose king was Ostrogotha, were called Ostrogoths, that is, eastern Goths, either from his name or from the place. But the rest were called Visigoths, that is, the Goths of the western country. (XIV 82)
Jordanes reported that Ostrogotha crossed the Danube during the reign of Philip the Arab and invaded the provinces of Moesia and Thrace. The later emperor Decius could not defeat him either, whereupon Ostrogotha again raided Roman territory.
- Now when the aforesaid Philip--who, with his son Philip, was the only Christian emperor before Constantine--ruled over the Romans, in the second year of his reign Rome completed its one thousandth year. He withheld from the Goths the tribute due them; whereupon they were naturally enraged and instead of friends became his foes. For though they dwelt apart under their own kings, yet they had been allied to the Roman state and received annual gifts. And what more? Ostrogotha and his men soon crossed the Danube and ravaged Moesia and Thrace. Philip sent the senator Decius against him. And since he could do nothing against the Getae, he released his own soldiers from military service and sent them back to private life, as though it had been by their neglect that the Goths had crossed the Danube. When, as he supposed, he had thus taken vengeance on his soldiers, he returned to Philip. But when the soldiers found themselves expelled from the army after so many hardships, in their anger they had recourse to the protection of Ostrogotha, king of the Goths. He received them, was aroused by their words and presently led out three hundred thousand armed men, having as allies for this war some of the Taifali and Astringi and also three thousand of the Carpi, a race of men very ready to make war and frequently hostile to the Romans. But in later times when Diocletian and Maximian were Emperors, the Caesar Galerius Maximianus conquered them and made them tributary to the Roman Empire. Besides these tribes, Ostrogotha had Goths and Peucini from the island of Peuce, which lies in the mouths of the Danube where they empty into the Sea of Pontus. He placed in command Argaithus and Guntheric, the noblest leaders of his race. They speedily crossed the Danube, devastated Moesia a second time and approached Marcianople, the famed metropolis of that land. Yet after a long siege they departed, upon receiving money from the inhabitants. (XVI 89-92)
Ostrogotha also fended off a challenge from the kinsfolk of the Goths, the Gepids, under the leadership of their king Fastida.
- For he sent ambassadors to Ostrogotha, to whose rule Ostrogoths and Visigoths alike, that is, the two peoples of the same tribe, were still subject. Complaining that he was hemmed in by rugged mountains and dense forests, he demanded one of two things,--that Ostrogotha should either prepare for war or give up part of his lands to them. Then Ostrogotha, king of the Goths, who was a man of firm mind, answered the ambassadors that he did indeed dread such a war and that it would be a grievous and infamous thing to join battle with their kin,--but he would not give up his lands. And why say more? The Gepidae hastened to take arms and Ostrogotha likewise moved his forces against them, lest he should seem a coward. They met at the town of Galtis, near which the river Auha flows, and there both sides fought with great valor; indeed the similarity of their arms and of their manner of fighting turned them against their own men. But the better cause and their natural alertness aided the Goths. Finally night put an end to the battle as a part of the Gepidae were giving way. Then Fastida, king of the Gepidae, left the field of slaughter and hastened to his own land, as much humiliated with shame and disgrace as formerly he had been elated with pride. The Goths returned victorious, content with the retreat of the Gepidae, and dwelt in peace and happiness in their own land so long as Ostrogotha was their leader. (XVII 98-100)
After his death, Jordanes mentions a new ruler of Goths, Cniva.