Moesia was an ancient region and later Roman province

Roman province

In Ancient Rome, a province was the basic, and, until the Tetrarchy , largest territorial and administrative unit of the empire's territorial possessions outside of Italy...

 situated in the Balkans

Balkans

The Balkans is a geopolitical and cultural region of southeastern Europe...

, along the south bank of the Danube River. It included territories of modern-day Southern Serbia (Moesia Superior), Northern Republic of Macedonia

Republic of Macedonia

Macedonia , officially the Republic of Macedonia , is a country located in the central Balkan peninsula in Southeast Europe. It is one of the successor states of the former Yugoslavia, from which it declared independence in 1991...

, Northern Bulgaria

Northern Bulgaria

Northern Bulgaria is the northern half of the territory of Bulgaria, located to the north of the main ridge of the Balkan Mountains which conventionally separates the country into a northern and a southern part...

, Romanian Dobrudja

Northern Dobruja

Northern Dobruja is the part of Dobruja within the borders of Romania. It lies between the lower Danube river and the Black Sea, bordered in south by Bulgarian Southern Dobruja.-Geography:...

, Southern Moldova

Moldova

Moldova , officially the Republic of Moldova is a landlocked state in Eastern Europe, located between Romania to the West and Ukraine to the North, East and South. It declared itself an independent state with the same boundaries as the preceding Moldavian Soviet Socialist Republic in 1991, as part...

, and Budjak

Budjak

Budjak or Budzhak is a historical region in the Odessa Oblast of Ukraine. Lying along the Black Sea between the Danube and Dniester rivers this multiethnic region was the southern part of Bessarabia...

 (Lower Moesia).
In ancient geographical sources, Moesia was bounded to the south by the Haemus

Haemus Mons

In earlier times the Balkan mountains were known as the Haemus Mons. It is believed that the name is derived from a Thracian word *saimon, 'mountain ridge', which is unattested but conjectured as the original Thracian form of Greek Haimos....

 (Balkans) 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 region was inhabited chiefly by Thracians, Dacians (Thraco

Thracians

The ancient Thracians were a group of Indo-European tribes inhabiting areas including Thrace in Southeastern Europe. They spoke the Thracian language – a scarcely attested branch of the Indo-European language family...

-Dacians

Dacians

The Dacians were an Indo-European people, very close or part of the Thracians. Dacians were the ancient inhabitants of Dacia...

), Illyrian

Illyrians

The Illyrians were a group of tribes who inhabited part of the western Balkans in antiquity and the south-eastern coasts of the Italian peninsula...

 and Thraco-Illyrian peoples.