The 390s refers to the decade running from AD 390 through AD 399, a transitional phase in Late Antiquity. It is marked by military conflict within the Roman world, decisive imperial legislation affecting religion, and developments among Christian leaders and thinkers that helped shape medieval Europe.

Politics and warfare

Major political events of the decade centered on the Roman Empire. In 394 the eastern emperor Theodosius I defeated the western usurper Eugenius and his general Arbogast at the Battle of the Frigidus, a clash that temporarily reunited the empire under Theodosius. The emperor’s death in 395 brought a permanent administrative division: his sons Arcadius and Honorius inherited the eastern and western halves respectively. The decade also saw growing influence of barbarian federates, notably Goths who had been settled within imperial territory and whose leaders, including Alaric, would become increasingly prominent.

Religion, law and society

The 390s witnessed energetic measures to favor Nicene Christianity. Imperial edicts in the early 390s restricted or outlawed many pagan practices and temple rites, accelerating the decline of traditional public cults. The relationship between church and imperial power was visible in episodes such as the aftermath of the 390 massacre at Thessalonica, when Bishop Ambrose of Milan publicly challenged Emperor Theodosius over the use of force.

Intellectual and spiritual life also flourished: Augustine of Hippo produced major works and rose to prominence in the late 390s, while Ambrose remained an influential ecclesiastical figure until his death in 397. These church leaders helped shape doctrine, pastoral practice, and the moral authority of bishops.

Notable figures and legacy

  • Theodosius I — emperor whose victories and legislation shaped imperial religion.
  • Ambrose of Milan — bishop and moral authority in imperial affairs.
  • Augustine of Hippo — theologian and writer whose late-4th-century works influenced Western Christianity.
  • Eugenius and Arbogast — western usurper and his general, defeated in 394.

Overall, the 390s stand out as a decade in which the Roman state moved decisively toward Christianization, internal conflicts altered political structures, and ecclesiastical leaders increased their social and moral influence—developments that set patterns for the fifth century and beyond.