Marcomannic Wars in the context of "Suebi"

The Vandals were a Germanic people who were first mentioned in the written records as the inhabitants of what is now Poland, during the period of the Roman Empire. Much later, in the 5th century, a group of Vandals led by kings established Vandal kingdoms, first within the Iberian Peninsula, and then in the western Mediterranean islands and North Africa.

Archaeologists associate the early Vandals with the Przeworsk culture, which has led to some authors equating them to the Lugii, who were another group of Germanic peoples associated with that same archaeological culture and region. Expanding into Dacia during the Marcomannic Wars and into Pannonia during the Crisis of the Third Century, the Vandals were confined to Pannonia by the Goths around 330 AD, where they received permission to settle from Constantine the Great. Around 400, raids by the Huns from the east forced many Germanic tribes to migrate west into the territory of the Roman Empire and, fearing that they might be targeted next, the Vandals were also pushed westwards, crossing the Rhine into Gaul along with other tribes in 406. In 409, the Vandals crossed the Pyrenees into the Iberian Peninsula, where the Hasdingi and the Silingi settled in Gallaecia (northwest Iberia) and Baetica (south-central Iberia).

Commodus (/ˈkɒmədəs/; Latin: [ˈkɔmmɔdʊs]; 31 August 161 – 31 December 192) was Roman emperor from 177 to 192, first serving as nominal co-emperor under his father Marcus Aurelius and then ruling alone from 180. Commodus's sole reign is commonly thought to mark the end of the Pax Romana, a golden age of peace and prosperity in the history of the Roman Empire.

Commodus accompanied his father during the Marcomannic Wars in 172 and on a tour of the Eastern provinces in 176. The following year, he became the youngest emperor and consul up to that point, at the age of 16. His solo reign saw less military conflict than that of Marcus Aurelius, but internal intrigues and conspiracies abounded, goading Commodus to an increasingly dictatorial style of leadership. This culminated in his creating a deific personality cult, including his performances as a gladiator in the Colosseum. Throughout his reign, Commodus entrusted the management of affairs to his palace chamberlain and praetorian prefects, namely Saoterus, Perennis, and Cleander.

A client kingdom or people in ancient Rome meant a kingdom or ancient people that was in the condition of "appearing" still independent, but in the "sphere of influence" and thus dependence of the neighboring Roman Empire. It was a form of modern protectorate, where the kingdom or territory in question was controlled (protected) by a stronger one (protector).

Roman Dacia (/ˈdeɪʃə/ DAY-shə; also known as Dacia Traiana (Latin for 'Trajan’s Dacia'); or Dacia Felix, lit. 'Fertile Dacia') was a province of the Roman Empire from 106 to 271–275 AD. Its territory consisted of what are now the regions of Oltenia, Transylvania and Banat (today all in Romania, except the last region which is split among Romania, Hungary, and Serbia). During Roman rule, it was organized as an imperial province on the borders of the empire. It is estimated that the population of Roman Dacia ranged from 650,000 to 1,200,000. It was conquered by Trajan (98–117) after two campaigns that devastated the Dacian Kingdom of Decebalus. However, the Romans did not occupy its entirety; Crișana, Maramureș, and most of Moldavia remained under the Free Dacians.

After its integration into the empire, Roman Dacia saw frequent administrative reorganization. In 119 under Hadrian, it was divided into two departments: Dacia Superior ("Upper Dacia") and Dacia Inferior ("Lower Dacia"; later named Dacia Malvensis). Between 124 and around 158, Dacia Superior was divided into two provinces, Dacia Apulensis and Dacia Porolissensis. The three provinces would later be unified in 166 and be known as Tres Daciae ("Three Dacias") due to the ongoing Marcomannic Wars. New mines were opened and ore extraction intensified, while agriculture, stock breeding, and commerce flourished in the province. Roman Dacia was of great importance to the military stationed throughout the Balkans and became an urban province, with about ten cities known and all of them originating from old military camps. Eight of these held the highest rank of colonia. Ulpia Traiana Sarmizegetusa was the financial, religious, and legislative center and where the imperial procurator (finance officer) had his seat, while Apulum was Roman Dacia's military center.

The barbarian invasions of the third century (212–305) constituted an uninterrupted period of raids within the borders of the Roman Empire, conducted for purposes of plunder and booty by armed peoples belonging to populations gravitating along the northern frontiers: Picts, Caledonians, and Saxons in Britain; the Germanic tribes of Frisii, Saxons, Franks, Alemanni, Burgundians, Marcomanni, Quadi, Lugii, Vandals, Juthungi, Gepids and Goths (Tervingi in the west and Greuthungi in the east), the Dacian tribes of the Carpi and the Sarmatian tribes of Iazyges, Roxolani and Alans, as well as Bastarnae, Scythians, Borani and Heruli along the Rhine-Danube rivers and the Black Sea.

Since the time of Marcus Aurelius during the Marcomannic Wars (166/167-189), Germanic-Sarmatian tribes had not exerted such strong pressure along the northern borders of the Roman Empire.

The Battle of Abritus also known as the Battle of Forum Terebronii occurred near Abritus (modern Razgrad) in the Roman province of Moesia Inferior in the summer of 251. It was fought between the Romans and a federation of Gothic and Scythian tribesmen under the Gothic king Cniva. The Roman army was soundly defeated, and Roman emperors Decius and Herennius Etruscus, his son, were both killed in battle. It was one of the worst defeats suffered by the Roman Empire against the Germanic tribes, rated by the Roman historian Ammianus Marcellinus as on par with the Battle of the Teutoburg Forest in 9, the Marcomannic invasion of Roman Italy in 170, and the Battle of Adrianople in 378.

The emperors' deaths led to more political instability at Rome; and the loss of the army allowed repeated barbarian incursions in the region for the next two decades.