Roman Dacia in the context of "Castra"

Hadrian (/ˈheɪdriən/ HAY-dree-ən; born Publius Aelius Hadrianus, 24 January 76 – 10 July 138) was Roman emperor from 117 to 138. Hadrian was born in Italica, in the present-day Andalusian province of Seville in southern Spain, an Italic settlement in Hispania Baetica; his gens Aelia came from the town of Hadria in eastern Italy. He was a member of the Nerva–Antonine dynasty.

Early in his political career, Hadrian married Vibia Sabina, grandniece of the ruling emperor, Trajan, and his second cousin once removed. The marriage and Hadrian's later succession as emperor were probably promoted by Trajan's wife Pompeia Plotina. Soon after his own succession, Hadrian had four leading senators unlawfully put to death, probably because they seemed to threaten the security of his reign; this earned him the senate's lifelong enmity. He earned further disapproval by abandoning Trajan's expansionist policies and territorial gains in Mesopotamia, Assyria, Armenia, and parts of Dacia. Hadrian preferred to invest in the development of stable, defensible borders and the unification of the Roman empire's disparate peoples and subjects. He was a promoter of philhellenism.

The Scordisci (Ancient Greek: Σκορδίσκοι; Latin: Scordiscii, Scordistae) were an Iron Age cultural group who emerged after the Celtic settlement of Southeast Europe, and who were centered in the territory of present-day Serbia, at the confluence of the Savus (Sava), Dravus (Drava), Margus (Morava) and Danube rivers. They were historically notable from the beginning of the third century BC until the turn of the common era, and consolidated into a tribal state. At their zenith, their core territory stretched over regions comprising parts of present-day Serbia, Croatia, Bulgaria and Romania, while their influence spread even further. After the Roman conquest in the 1st century AD, their territories were included into the Roman provinces of Pannonia, Moesia and Dacia.

Dacia (/ˈdeɪʃə/, DAY-shə; Latin: [ˈd̪aː.ki.a]; Ancient Greek: Δακία) was the land inhabited by the Dacians, its core in Transylvania, stretching to the Danube in the south, the Black Sea in the east, and the Tisza in the west. The Carpathian Mountains were located in the middle of Dacia. It thus roughly corresponds to present-day Romania, as well as parts of Moldova, Bulgaria, Serbia, Hungary, Slovakia, Czech Republic, Poland and Ukraine.

A Dacian kingdom that united the Dacians and the Getae was formed under the rule of Burebista in 82 BC and lasted until the Roman conquest in AD 106. As a result of the wars with the Roman Empire, after the conquest of Dacia, the population was dispersed, and the capital city, Sarmizegetusa Regia, was destroyed by the Romans. However, the Romans built a settlement bearing the same name, Ulpia Traiana Sarmizegetuza, 40 km away, to serve as the capital of the newly established Roman province of Dacia. A group of "Free Dacians" may have remained outside the Roman Empire in the territory of modern-day Northern Romania until the start of the Migration Period.

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).

The Bastarnae, Bastarni or Basternae, also known as the Peuci or Peucini, were an ancient people who are known from Greek and Roman records to have inhabited areas north and east of the Carpathian Mountains between about 300 BC and about 300 AD, stretching in an arc from the sources of the Vistula in present-day Poland and Slovakia, to the Lower Danube, and including all or most of present-day Moldava. The Peucini were sometimes described as a subtribe, who settled the Peuke Island in the Danube Delta, but apparently due to their importance their name was sometimes used for the Bastarnae as a whole. Near the sources of the Vistula another part of the Bastarnae were the Sidones, while the Atmoni, another tribe of the Bastarnae are only mentioned in one listing by Strabo.

The earliest Graeco-Roman historians to refer to the Bastarnae imply that they were culturally Celtic. Also consistent with connections to the cultures to their west, later Roman-era sources state directly that they spoke Germanic languages, and could be considered Germanic peoples. In contrast, like other peoples who lived in this geographical region, Graeco-Roman writers also sometimes referred to the Bastarnae as a "Scythian" or "Sarmatian" people, but this was a reference to their location, and customs, rather than a linguistic category. Although largely sedentary, at least one Roman writer, Tacitus, stated that the Bastarnae had adopted some Sarmatian customs. So far, no archaeological sites have been conclusively attributed to the Bastarnae. The archaeological horizon most often associated by scholars with the Bastarnae is the Poieneşti-Lucașeuca culture.

The Gepids (Latin: Gepidae, Gipedae; Ancient Greek: Γήπαιδες, romanized: Gḗpaides) were an East Germanic tribe who lived in the area of modern Romania, Hungary, and Serbia, roughly between the Tisza, Sava, and Carpathian Mountains. They were said to share the religion and language of the Goths and Vandals.

They are first mentioned by Roman sources in the third century. In the fourth century, they were among the peoples incorporated into the Hunnic Empire, within which they formed an important part. After the death of Attila, the Gepids under their leader Ardaric, led an alliance of other peoples who had been in the empire, and defeated the sons of Attila and their remaining allies at the Battle of Nedao in 454. The Gepids and their allies subsequently founded kingdoms on the Middle Danube, bordering on the Roman Empire. The Gepid Kingdom was one of the most important and long-lasting of these, centered on Sirmium, and sometimes referred to as Gepidia. It covered a large part of the former Roman province of Dacia, north of the Danube, and compared to other Middle Danubian kingdoms it remained relatively uninvolved with Rome.

Aurelian (/ɔːˈriːliən/; Latin: Lucius Domitius Aurelianus; 9 September c. 214 – c. November 275) was a Roman emperor who reigned from 270 to 275 during the Crisis of the Third Century. As emperor, he won an unprecedented series of military victories which reunited the Roman Empire after it had nearly disintegrated under the pressure of barbarian invasions and internal revolts. For his success in restoring the Empire's territorial integrity, Aurelian was honored with the title Restitutor Orbis ("Restorer of the World"). Born in modest circumstances, most likely in Moesia Superior, he entered the Roman army in 235 and climbed up the ranks. He went on to lead the cavalry of the emperor Gallienus, until Gallienus' assassination in 268. Following that, Claudius Gothicus became emperor until his own death in 270. Claudius' brother Quintillus then ruled for three months, before Aurelian took the empire for himself. Aurelian was chosen Roman emperor by the Illyriciani as one of themselves.During his reign, he defeated the Alamanni after a devastating war. He also defeated the Goths, Vandals, Juthungi, Sarmatians, and Carpi. Aurelian restored the Empire's eastern provinces after his conquest of the Palmyrene Empire in 273. The following year he conquered the Gallic Empire in the west, reuniting the Empire in its entirety. He was also responsible for the construction of the Aurelian Walls in Rome, the abandonment of the province of Dacia, and monetary reforms attempting to curb the devaluation of the Roman currency.Although Domitian, two centuries earlier, was the first emperor who had demanded to be officially hailed as dominus et deus ('master and god'), these titles never occurred in written form on official documents until the reign of Aurelian. His successes were instrumental in ending the crisis.

The Battle of Lugdunum, also called the Battle of Lyon, was fought on 19 February 197 at Lugdunum (modern Lyon, France), between the armies of the Roman emperor Septimius Severus and of the Roman usurper Clodius Albinus. Severus' victory finally established him as the sole emperor of the Roman Empire following the Year of the Five Emperors and immediate aftermath.

This battle is said to be the largest, most hard-fought, and bloodiest of all clashes between Roman forces. According to English historian Edward Gibbon, the Roman historian Cassius Dio placed the total number of Roman soldiers engaged for both sides combined at 150,000. Historian Michael Kulikowski states that Severus led the much larger force with the combined legions of Dacia and the Danubian provinces. Historian A. J. Graham supports Gibbon's number of 150,000 soldiers in total, rather than the sometimes cited number of 300,000 in total and therefore 150,000 on each side, which he states to be a commonly accepted mistranslation of Cassius Dio's original language. Graham also analyses the possible forces available to Albinus and states that the numbers on each side could have been roughly equal.