The imperial successor Trebonianus Gallus (r.  251–253) pledged to pay an annual tribute if the invaders left, however, he did not keep his promise, which provoked new attacks in 253, although the governor and future emperor Aemilianus (r.  253) managed to stop these raids.

Two factors can be distinguished that contributed to the growing discontent of the population living north of the Danube during the 3rd century, which culminated in the outbreak of the Gothic War: The first and most important was that since the time of Severus Alexander (r.  222–235), there were continuous relocations of new villages close to the Danubian border.

[1] At that time it is reported that the cities of Olbia and Tiras, former Greek colonies in present-day Ukraine, were destroyed by warriors of a new and powerful people who were ravaging that region.

Subsequently, in the spring of 238, groups of warriors of this same people, generically referred to as Scythians,[2] crossed the lands of the Carpiani, Dacians, and invaded Lower Moesia, where they captured and plundered the city of Istros.

[6] According to De origine actibusque Getarum by the Roman historian Jordanes, as a consequence of suspending the payment of tribute at the end of 248, Ostrogotha, king of the Ostrogoths and Visigoths, crossed the Danube with an army made up of Goths and allied Germanic-Sarmat tribes (Taifals, Bastarnae, Hasdingi and Carpiani), estimated by the author to number 300,000 men,[note 1] and led an invasion of Moesia and Thracia.

[16] Cniva divided his army into two parts and sent about 20,000 of his soldiers to attack Moesia, which at that time was unprotected, and then to Philippopolis (present-day Plovdiv, in Bulgaria), while he himself led 70,000 men to Euscia (Novae).

[17] With the departure of Cniva, Decius crossed Mount Haemus, perhaps through the Shipka Pass, and camped at Beroe (present-day Stara Zagora), where he was later defeated in a surprise attack by the Gothic king.

After intercepting the Germanic partisans and repairing the Danubian fortifications, he set out to fight the Goths, who were surrounded by the numerically superior Roman forces as they attempted to retreat.

[26] Possibly among the freedmen was Cnaeus Valerius Serapion, who dedicated an undated altar, found in Apulon (now Alba Iulia) in Roman Dacia, thanking them for his ransom from the Carpiani (Liberatus a Carpis).

In 256 and 257, taking advantage of the political instability of the empire, a coalition of barbarian tribes, led by the Carpiani, invaded Moesia, sacked Thracia and besieged Thessaloniki in Macedonia.