阴土兔年 (female Earth-Rabbit) 506 or 125 or −647 — to — 阳金龙年 (male Iron-Dragon) 507 or 126 or −646
Year 380 (CCCLXXX) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Augustus (or, less frequently, year 1133 Ab urbe condita). The denomination 380 for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Rome's enemies (the Germans, Sarmatians and Huns) are taken into Imperial service; as a consequence, barbarian leaders begin to play an increasingly active role in the Roman Empire.
November 24 – Theodosius I makes his adventus, or formal entry, into Constantinople.
Easter Island, in the south Pacific Ocean, has been occupied by Neolithic seafarers under Hotu Matu'a ("supreme chief"), who about this time begin to fortify the island.
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Arts and sciences
Important works on mathematics and astronomy are written in Sanskrit.