What is "moesia"

Moesia (, , or ; Latin: Moesia; ) was an ancient region and later Roman province situated in the Balkans, along the south bank of the Danube River. It included most of the territory of modern-day Serbia (without Vojvodina) and the northern parts of the modern Republic of Macedonia, (Moesia Superior), as well Northern Bulgaria and Romanian Dobrudja, (Moesia Inferior).