In Roman literature of the early 1st century CE, the Moesi ( or ; Ancient Greek: Μοισοί, Moisoí or Μυσοί, Mysoí; Latin: Moesi or Moesae) appear as a tribe who lived in the region around the Timok River to the south of the Danube. The Moesi do not appear in ancient sources before Augustus's death in 14 CE and are mentioned only by three authors dealing with the Roman warfare in the region and the ethnonymic situation between mid-1st century BC and mid-1st century CE: Ovid, Strabo and Livy. A Paleo-Balkan tribe known as the Moesi never actually existed in the Danube area before that period, it was a Roman invention. The ethnonym was transplanted from Asia Minor Mysians to the Balkans by the Romans as a replacement of the name of the Dardani who lived in the territory that later became the province of Moesia Superior. This decision in Roman literature is linked to the appropriation of the name Dardani in official Roman ideological discourse as Trojan ancestors of the Romans and the creation of a fictive name for the actual Dardani who were seen as barbarians and antagonists of Rome in antiquity. This new fictive Augustan terminology was illogically and controversially argumented by Strabo as the result of Aelius Catus's displacement of 50,000 Getae from the north to the south of the Danube, who settled areas in the north-eastern parts of the later province of Moesia Superior, thereafter being called "Moesi".
The Latin name Moesia was given first to the province of Moesia Superior and expanded into Moesia Inferior along the Danube. After the recreation of Dardania, Moesia referred to Moesia Prima, the northern part of Moesia Superior. A civitas of the Moesi which was reorganized as a Roman colony was located around Ratiaria in the first century AD.