Sarmatians in the context of "Early Slavs"

Theodosius I (Ancient Greek: Θεοδόσιος Theodosios; 11 January 347 – 17 January 395), also known as Theodosius the Great, was Roman emperor from 379 to 395. He won two civil wars and was instrumental in establishing the Nicene Creed as the orthodox doctrine for Nicene Christianity. Theodosius was the last emperor to rule the entire Roman Empire before its administration was permanently split between the Western Roman Empire and the Eastern Roman Empire. He ended the Gothic War (376–382), but did so on terms disadvantageous to the empire, with the Goths remaining and politically autonomous within Roman territory, albeit as nominal allies.

Born in Hispania, Theodosius was the son of a high-ranking general of the same name, Theodosius the Elder, under whose guidance he rose through the ranks of the Roman army. Theodosius held independent command in Moesia in 374, where he had some success against the invading Sarmatians. Not long afterwards, he was forced into retirement, and his father was executed under obscure circumstances. Theodosius soon regained his position following a series of intrigues and executions at Emperor Gratian's court. In 379, after the eastern Roman emperor Valens was killed at the Battle of Adrianople against the Goths, Gratian appointed Theodosius as a successor with orders to take charge of the military emergency. The new emperor's resources and depleted armies were not sufficient to drive the invaders out; in 382 the Goths were allowed to settle south of the Danube as autonomous allies of the empire. In 386, Theodosius signed a treaty with the Sasanian Empire which partitioned the long-disputed Kingdom of Armenia and secured a durable peace between the two powers.

A barbarian is a person or tribe of people that is perceived to be primitive, savage, and warlike. A "barbarian" may also be an individual reference to an aggressive, brutal, cruel, and insensitive person, particularly one who is also dim-witted, while cultures, customs and practices adopted by peoples and countries perceived to be primitive may be referred to as "barbaric".

The term originates from the Ancient Greek: βάρβαρος (barbaros; pl. βάρβαροι barbaroi). In ancient Greece, the Greeks used the term not only for those who did not speak Greek and follow classical Greek customs, but also for Greek populations on the fringe of the Greek world with peculiar dialects. In ancient Rome, the Romans adapted and applied the term to tribal non-Romans such as the Xiongnu, Mongols, Germans, Celts, Iberians, Helvetii, Thracians, Illyrians, and Sarmatians. In the early modern period and sometimes later, the Byzantine Greeks used it for the Turks in a clearly pejorative manner.

Diocletian (/ˌdaɪ.əˈkliːʃən/ DY-ə-KLEE-shən; Latin: Gaius Aurelius Valerius Diocletianus; Ancient Greek: Διοκλητιανός, romanized: Diokletianós; 242/245 – 311/312), nicknamed Jovius, was Roman emperor from 284 until his abdication in 305. He was born Diocles to a family of low status in the Roman province of Dalmatia. As with other Illyrian soldiers of the period, Diocles rose through the ranks of the military early in his career, serving under Aurelian and Probus, and eventually becoming a cavalry commander for the army of Emperor Carus. After the deaths of Carus and his son Numerian on a campaign in Persia, Diocles was proclaimed emperor by the troops, taking the name "Diocletianus". The title was also claimed by Carus's surviving son, Carinus, but Diocletian defeated him in the Battle of the Margus.

Diocletian's reign stabilized the empire and ended the Crisis of the Third Century. He initiated the process of the Roman Empire split and appointed fellow officer Maximian as Augustus, co-emperor, in 286. Diocletian reigned in the Eastern Empire, and Maximian reigned in the Western Empire. Diocletian delegated further on 1 March 293, appointing Galerius and Constantius as junior colleagues (each with the title Caesar), under himself and Maximian respectively. Under the Tetrarchy, or "rule of four", each tetrarch would rule over a quarter-division of the empire. Diocletian secured the empire's borders and purged it of all threats to his power. He defeated the Sarmatians and Carpi during several campaigns between 285 and 299, the Alamanni in 288, and usurpers in Egypt between 297 and 298. Galerius, aided by Diocletian, campaigned successfully against Persia, the empire's traditional enemy, and in 299, he sacked their capital, Ctesiphon. Diocletian led the subsequent negotiations and achieved a lasting and favorable peace.

The Vistula Veneti, also called Baltic Veneti, Venedi or Venethi, were an Indo-European people that inhabited the lands of central Europe east of the Vistula River and the Bay of Gdańsk. Ancient Roman geographers first mentioned Venedi in the 1st century AD, differentiating a group of peoples whose manner and language differed from those of the neighbouring Germanic and Sarmatian tribes. In the 6th century AD, Byzantine historians described the Veneti as the ancestors of the Slavs who, during the second phase of the Migration Period, crossed the northern frontiers of the Byzantine Empire.

The Alans (Latin: Alani) were an ancient and medieval Iranic nomadic pastoral people who migrated to what is today North Caucasus; some continued on to Europe and later North Africa. They are generally regarded as part of the Sarmatians, and possibly related to the Massagetae. Modern historians have connected the Alans with the Central Asian Yancai of Chinese sources and with the Aorsi of Roman sources. Having migrated westwards and becoming dominant among the Sarmatians on the Pontic–Caspian steppe, the Alans are mentioned by Roman sources in the 1st century CE. At that time they had settled the region north of the Black Sea and frequently raided the Parthian Empire and the South Caucasus provinces of the Roman Empire. From 215 to 250 CE the Goths broke their power on the Pontic Steppe, thereby assimilating a sizeable portion of the associated Alans.

Upon the Hunnic defeat of the Goths on the Pontic Steppe around 375 CE, many of the Alans migrated westwards along with various Germanic tribes. They crossed the Rhine in 406 along with the Vandals and Suebi, settling in Orléans and Valence. Around 409 they joined the Vandals and Suebi in crossing the Pyrenees into the Iberian Peninsula, settling in Lusitania and Hispania Carthaginensis. The Iberian Alans, soundly defeated by the Visigoths in 418, subsequently surrendered their authority to the Hasdingi Vandals. In 428 CE, the Vandals and Alans crossed the Strait of Gibraltar into North Africa, where they founded a kingdom which lasted until its conquest by forces of the Byzantine Emperor Justinian I in 534.

The Eurasian Steppe, also called the Great Steppe or The Steppes, is the vast steppe ecoregion of Eurasia in the temperate grasslands, savannas and shrublands biome. It stretches through Manchuria, Mongolia, Xinjiang, Kazakhstan, Siberia, European Russia, Ukraine, Moldova, Romania, Bulgaria, Hungary and Slovakia.

Since the Paleolithic age, the Steppe Route has been the main overland route between Eastern Europe, North Asia, Central Asia and East Asia economically, politically, and culturally. The Steppe route is a predecessor not only of the Silk Road, which developed during antiquity and the Middle Ages, but also of the Eurasian Land Bridge in the modern era. It has been home to nomadic empires and many large tribal confederations and ancient states throughout history, such as the Xiongnu, Scythia, Cimmeria, Sarmatia, Hunnic Empire, Sogdia, Xianbei, Mongol Empire, Magyar tribes, and Göktürk Khaganate.

Constantine II (Latin: Flavius Claudius Constantinus; 316–340) was Roman emperor from 337 to 340. The son of the emperor Constantine I, he was proclaimed caesar by his father shortly after his birth. He was associated with military victories over the Sarmatians, Alamanni and Goths during his career, for which he was granted a number of victory titles. He held the consulship four times – in 320, 321, 324, and 329.

Constantine I had arranged for his sons to share power with their cousins Dalmatius and Hannibalianus, but this was not accepted by Constantine II and his brothers. As a result, Constantine II's brother Constantius II ordered the killings of numerous male relatives following Constantine I's death, including Dalmatius and Hannibalianus, thus eliminating any possible opponents to the succession of Constantine I's sons. Constantine II then ascended to the throne alongside his two younger brothers, ruling Gaul, Hispania, and Britain. However, his belief in his rights of primogeniture and attempts to exert them over his youngest brother Constans caused conflict, which ended with his death in a failed invasion of Italy in 340. Constans subsequently took control of Constantine's territories, with the latter being subjected to damnatio memoriae.