The modern Romanian state was formed in 1859 through a personal union of the Danubian Principalities of Moldavia and Wallachia. The new state, officially named Romania since 1866, gained independence from the Ottoman Empire in 1877.

The Eastern Roman, or Byzantine, Empire was known during the Middle Ages as the Roman Empire, or more commonly Romania (Ρωμανία in Greek; compare with the modern name Ρουμανία "Roumanía" for Romania).

When Austria-Hungary was defeated in World War I, the Romanians of Transylvania in late 1918 proclaimed the land united with Romania. In 1920 the Allies confirmed the union in the Treaty of Trianon.

Some scholars claim that the ancestors of Romanians came from southern Europe, south of the Danube River. Others claim their ancestors were indigenous to the Balkans. Either way, Romanians entered the region in the late first/early second century CE and encountered people they called the Dacians.