thumb|350px|Roman Moesia in 250 AD, divided into the provinces of Moesia Superior to the west and Moesia Inferior to the east
Moesia (; Latin: Moesia; ) was a Roman province situated in the Haemus Peninsula, south of the Danube River. Created after the Danubian-Hæmus conquest during the reign of Augustus, Moesia included most of the territory of modern eastern Serbia, Kosovo, north-eastern Albania, northern parts of North Macedonia (Moesia Superior), Northern Bulgaria, Northern Dobruja and small parts of Southern Ukraine (Moesia Inferior).
Extension
The Roman province of Moesia (both Moesia Superior and Moesia Inferior) was bounded to the south by the Haemus (Balkan Mountains) and Scardus (Šar) mountains, to the west by the Drinus (Drina) river, on the north by the Donaris (Danube) and on the east by the Euxine (Black Sea). The Dardani continued to fight against Rome and its proconsuls, and were finally defeated probably by Marcus Antonius in 39 BC or by Marcus Licinius Crassus in 29/8 BC. The Romans created the province of Moesia also including the territory of Dardania. After the Roman emperor Domitian divided the province of Moesia into Moesia Superior and Moesia Inferior in 86 AD, the Dardani were located in southern Moesia Superior. Emperor Diocletian later (284) made Dardania into a separate province with its capital at Naissus (Niš). The Romans found an ancient formed economy in Dardania, based on agriculture and animal husbandry, mining and metallurgy, in different handicrafts and in trade. The Romans focused especially in exploitation of mines, same as in other provinces, and in road construction.
Parts of the later province of Moesia belonged, before the Roman rule, to the polity of Burebista, a Getae (Dacian) king who established his rule over a large part of the northern Balkans between 82 BC and 44 BC. He led raids for plunder and conquest across Central and Southeastern Europe, subjugating most of the neighbouring tribes. After his assassination in a palace intrigue, the empire was divided into several smaller states. In 74 BC, C. Scribonius Curio, proconsul of Macedonia, took an army as far as the Danube and chased the Geto-Dacians to the border of their remote country. The expansion of the Dacians on the middle and lower reaches of the Danube worried the Romans and destruction of Dacian power became one of Julius Caesar's key political objectives, who made plans to launch an offensive from Macedonia in about 44 BC.
Once Augustus had established himself as sole ruler of the Roman state in 30 BC after the naval Battle of Actium in 31 BC, he took up Caesar's project and aimed to advance the empire's south-eastern European border from Macedonia to the line of the Danube. The main objective was to increase strategic depth between the border and Italy and also to provide a major river supply route between the Roman armies in the region. The lower Danube was given priority over the upper Danube and required the annexation of Moesia. It was therefore necessary to conquer the tribes who dwelt south of the Danube namely (from west to east) the Triballi, Moesi, Getae and the Bastarnae who had recently subjugated the Triballi, and with their capital at Oescus. Augustus also wanted to avenge the defeat of Gaius Antonius Hybrida at Histria 32 years before and to recover the lost military standards held in the powerful fortress of Genucla.
Marcus Licinius Crassus, grandson of Crassus the triumvir was appointed for the task. He was an experienced general at 33 years of age, and proconsul of Macedonia from 29 BC. After a successful campaign against the Moesi, he drove the Bastarnae back toward the Danube and finally defeated them in pitched battle, killing their King Deldo in single combat. Augustus formally proclaimed this victory in 27 BC in Rome but blocked Cassius' entitlement to the Spolia opima and use of the term imperator apparently in favour of his own prestige.
Moesia was split off as a separate military command some time before 10 BC.
As a result of the Dacians constant looting that occurred whenever the Danube froze, Augustus decided to send against them some of his proven generals such as Sextus Aelius Catus and Gnaeus Cornelius Lentulus Augur (sometime between 1-11 AD). Lentulus pushed them back across the Danube and placed numerous garrisons on the right bank of the river to defend against possible and future incursions. These became the Moesian Limes frontier defensive system that was developed further later.
Roman Province
The region, however, was not organised as a province until the last years of Augustus' reign; in 6 AD, mention is made of its governor, Caecina Severus. As a province, Moesia was under an imperial consular legate (who probably also had control of Achaea and Macedonia).
In 86 AD the Dacian king Duras attacked Moesia after which the Roman emperor Domitian personally arrived in Moesia and reorganised it in 87 into two provinces, divided by the river Cebrus (Ciabrus):
Gothic raids
thumb|Gothic invasions of 250–251
The first incursion in Moesia that can be attributed to Goths is by the Costoboci in 170 in the Marcomannic Wars when they destroyed Tropaeum Traiani.
In 238 the Carpi sacked Histria and Tropaeum Traiani. Afterwards Moesia was frequently invaded or raided by the Dacian Carpi, and the East Germanic tribes of the Goths.
In the Gothic War (248–253), the Gothic king Cniva captured the city of Philippopolis and then inflicted a devastating defeat upon the Romans at the Battle of Abrittus, in which the Roman Emperor Decius was killed, one of the most disastrous defeats in the history of the Roman army.
Retreat from Dacia
thumb|300px|Provinces in 400 AD
After the abandonment of Roman Dacia to the Goths by Aurelian (270–275) and the transfer of the Roman citizens from the former province to the south of the Danube, the central portion of Moesia took the name of Dacia Aureliana (later divided into Dacia Ripensis