The Moesian Federation (Serbo-Croatian: Mезијских Федерација / Mezijskih Federacija; Italian: Federazione Mesiana), known informally as Moesia, is a sovereign state situated in the Balkans of Europe. A federation of republics, the Moesian Federation consists of the Republic of Croatia, Republic of Serbia and the Bosnian Republics. It borders Italy, Slovenia, Hungary, Romania, Bulgaria and Montenegro. With a population of over 24 million as of 2016, the Moesian Federation is the third most populous state in the Mediterranean Union and the tenth most populous on the entire continent.
Historically, Moesia was an ancient region situated in the Balkans along the south bank of the Danube River. The region became divided between two Roman provinces: Moesia Superior and Moesia Inferior; the former corresponding to the eastern parts of the modern-day Serbian Republic (Vojvodina exempt) and the northern parts of Bulgarian Macedonia while the latter corresponds to northern Bulgaria and Romanian Dobrudja.