380s

• January or February – Emperor Theodosius I is baptized.
• February 27 – Edict of Thessalonica: Theodosius I, with co-emperors Gratian and Valentinian II, say that all Roman citizens should become Christians.
• The Rock of Cashel is built in Ireland.
• The Visigothic chieftain Fritigern dies. His rival Athanaric becomes king of the entire Gothic nation.

Births

• Aelia Eudoxia, empress and wife of Arcadius
• Alexius, Eastern saint
• Eucherius, bishop of Lyon
• Hephaistio of Thebes, Egyptian astrologer

Deaths

• Peter II, Patriarch of Alexandria
• Samudragupta, ruler of the Gupta Empire
• Wang Fahui, empress of the Jin Dynasty

• Roman Emperor Gratian moves the capital to Mediolanum (modern Milan).
• The Visigothic chieftain Athanaric becomes the first foreign king to visit the East Roman capital of Constantinople.
• Flavian succeeds Meletius as Patriarch of Antioch.
• Timothy succeeds Peter as Patriarch of Alexandria.

Births

• Helian Bobo, emperor of the Chinese Xiongnu state Xia

Deaths

• Athanaric, king of the Visigoths

• Roman Emperor Gratian removes the Altar of Victory from the Senate.

Births

• Jin Andi, emperor of the Eastern Jin Dynasty
• Sima Yuanxian, regent during the Jin Dynasty

• Niall of the Nine Hostages becomes the first High King of Ireland.
• Hadrian's Wall is overrun by the Picts.
• January 19 – Arcadius becomes Roman Emperor.
• Roman troops in Britain call Magnus Maximus Emperor. He crosses over to the continent and makes Trier his capital.
• King Ardashir II dies after a 4-year reign. He is succeeded by his son Shapur III.

Births

• Lupus of Troyes, French bishop and saint

Deaths

• August 25 – Gratian, Roman Emperor
• December 10 – Pope Damasus I
• Frumentius, the "Apostle to Ethiopia"

• Magnus Maximus returns to Britain to help them with the Barbarians raids.
• An edict of Theodosius I closes pagan temples in the Nile Valley.
• King Shapur III signs a treaty with Theodosius I. Armenia is divided in two kingdoms.
• December 17 – Pope Siricius succeeds Damasus I as the 38th pope.

Births

• September 9 – Honorius, Roman Emperor
• Chu Lingyuan, last empress of the Jin Dynasty
• Maria, empress and daughter of Stilicho
• Sengzhao, Chinese Buddhist
• Wang Shen'ai, empress of the Jin Dynasty

Deaths

• December 11 – Pope Damasus I
• Chu Suanzi, empress of the Jin Dynasty
• Geungusu, king of Baekje
• Murong Hong, founder of the Xianbei state Western Yan

• Jinsa of Baekje becomes the 16th king of the ancient Korean kingdom of Baekje.
• Copper extraction and casting begins in the mines of Kansanshi in southernmost Africa.
• Ammianus Marcellinus begins writing a history covering the years 96 to 378.
• The Serapeum in Alexandria is destroyed.
• Aurelios Zopyros becomes the last reported athlete at the Ancient Olympic Games.

Births

• Avitus, Western Roman Emperor
• Murong Chao, emperor of the Xianbei state Southern Yan
• Murong Xi, emperor of the Xianbei state Later Yan
• Saint Patrick, missionary in Ireland
• Paulus Orosius, historian and theologian
• Xie Lingyun, Chinese poet of the Southern and Northern Dynasties

Deaths

• Aelia Flaccilla, Roman empress and wife of Theodosius I
• Chimnyu, king of Baekje (Korea)
• Dao An, Buddhist monk of the Jin Dynasty
• Fú Jiān, emperor of the Chinese Di state Former Qin
• Murong Wei, emperor of the Xianbei state Former Yan

• The Greuthungi cross the Danube to raid the Roman garrisons.
• Magnus Maximus invades Italy.
• The Northern Wei Dynasty begins in China.

Births

• Jin Gongdi, last emperor of the Jin Dynasty
• Nestorius, founder of Nestorianism

Deaths

• Cyril of Jerusalem, theologian and saint
• Duan Sui, ruler of the Western Yan
• Fu Pi, emperor of the Former Qin
• Jin Feidi, emperor of the Jin Dynasty
• Murong Chong, emperor of the Western Yan
• Murong Yao, emperor of the Western Yan
• Murong Yi, ruler of the Western Yan
• Murong Zhong, emperor of the Western Yan

• Spring – Emperor Theodosius I increases the taxes in Antioch. The peasants start a riot.
• Magnus Maximus invades Italy. Emperor Valentinian II, age 16, is forced out of Rome.
• Winter – Emperor Theodosius I takes Valentinian II into protection.

Deaths

• Aelia Flaccilla, wife of Theodosius I
• Alatheus, chieftain of the Ostrogoths
• Saint Monica, mother of Augustine of Hippo

• Battle of the Save: Emperor Theodosius I defeats Magnus Maximus near Emona.
• Valentinian II is restored as Roman Emperor.
• August 28 – Magnus Maximus surrenders at Aquileia and is executed.
• Bahram IV becomes the twelfth Sassanid king of Persia.
• Emperor Chandragupta II, ruler of the Gupta Empire, begins a war against the Shaka Dynasty in West India.

Births

• Yao Hong, emperor of the Chinese Qiang state Later Qin

Deaths

• Flavius Victor, son of Magnus Maximus and co-emperor
• Qifu Guoren, ruler of the Xianbei state Western Qin
• Shapur III, king of the Sassanid Empire

• All pagan buildings in Alexandria are destroyed by fire. This includes the library.

Births

• Geiseric, king of the Vandals and Alans

Deaths

• Mao, Chinese empress and wife of Fu Deng
• January 25 – Gregory Nazianzus, theologian