Margus was an ancient Roman city situated at locality of present-day Požarevac (Serbia).
Before the Roman conquest, the area was inhabited by Thracians, Dacians[citation needed] and Celts.
Nearby Viminacium was the provincial capital of Moesia Superior, of which Margus was part.
[citation needed] In 435, the city of Margus, under the Eastern Roman Empire, was the site of a treaty between the Byzantine Empire and the Hun leaders Attila and Bleda.
One pretext for the Hun invasion of the Eastern Roman Empire in 442 was that the Bishop of Margus had crossed the Danube to ransack and desecrate the royal Hun graves on the north bank of the Danube.