The union of Bessarabia with Romania was proclaimed on April 9 [O.S. March 27] 1918 by Sfatul Țării, the legislative body of the Moldavian Democratic Republic. This state had the same borders of the region of Bessarabia, which was annexed by the Russian Empire following the Treaty of Bucharest of 1812 and organized first as an Oblast (autonomous until 1828) and later as a Governorate. Under Russian rule, many of the native Tatars were expelled from parts of Bessarabia and replaced with Moldavians, Wallachians, Bulgarians, Ukrainians, Greeks, Russians, Lipovans, Cossacks, Gagauzes and other peoples, although colonization was not limited to formerly Tatar-inhabited lands. Russia also tried to integrate the region by imposing the Russian language in administration and restricting education in other languages, notably by later banning the use of Romanian in schools and print.
The beginning of World War I saw an increase in national awareness among the Bessarabians, and, following the beginning of the Russian Revolution in 1917, Bessarabia proclaimed its own parliament, the Sfatul Țării, which declared the Moldavian Democratic Republic. Following a Romanian military intervention, with the Romanian Army firmly in control of the region, the Sfatul Țării voted for independence and later proclaimed, on April 9 [O.S. March 27] 1918, its union with the Kingdom of Romania. Although the unification was made under various conditions, all of these except the promise of an agrarian reform, which was carried out, were later abandoned by a minority of the Sfatul. Later, the Romanian administration swiftly dissolved the assembly and rejected the protests of the former deputies. In the peace talks after World War I, the European powers awarded Bessarabia to Romania, although the newly formed Russian SSR, and the United States never recognized this.