The union of Bessarabia with Romania was proclaimed on 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.
The beginning of World War I caused 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 proclaimed on unification 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, supported by the United States, never recognized this.
However, the situation in Bessarabia would change after the signing of the Molotov–Ribbentrop Pact between the Soviet Union (USSR) and Nazi Germany, in which the latter expressed its disinterest in the region. This allowed the USSR to send an ultimatum to Romania, which was now diplomatically isolated with the outbreak of World War II, on 26 June 1940 in which it demanded Bessarabia and also Northern Bukovina. After Romania accepted it, the USSR occupied these territories, ending Romanian rule in the zone. Bessarabia was organized and split between the Ukrainian SSR and the new Moldavian SSR, which gained independence in 1991 as Moldova. Ever since, there has been a minority but growing movement to reunite the region with Romania, with supporters in Romania and Moldova commemorating the day of the union, 27 March, on the Day of the Union of Bessarabia with Romania.
Governorate of Bessarabia
The 1812 Treaty of Bucharest between the Ottoman Empire and the Russian Empires provided for Russian annexation of the eastern part of the territory of the Principality of Moldavia, as well as the Turkish-ruled regions of Khotyn and Budjak (Southern Bessarabia). At first, the Russians used the name "Oblast of Moldova and Bessarabia", allowing a large degree of autonomy, but in 1828 Russia suspended the self-administration and called it the Governorate of Bessarabia, or simply Bessarabia. While the northeastern part of Moldavia, called Bukovina, was similarly annexed by the Austrian Empire, the western part of Moldavia remained an autonomous principality, and in 1859, united with Wallachia to form the Kingdom of Romania. In 1856, the Treaty of Paris returned the south of Bessarabia to Moldavia, but in 1878, the Kingdom of Romania returned them to the Russian Empire as a result of the Treaty of Berlin.
At the time of annexation, Moldavian population predominated in Bessarabia. The colonization of the region in the 19th century led to a large increase in the Russian, Ukrainian, Lipovan, and Cossack population in the region; this together with a large influx of Bulgarian immigrants increased the Slavic population to more than a fifth of the total population by 1920. Other groups, such as Gagauz, Jews, and Germans also settled in the region during the Russian rule.
The Tsarist policy in Bessarabia was in part aimed at denationalization of the Moldavian element by forbidding after the 1860s education and Liturgy in Romanian. However, the effect was an extremely low literacy rate (in 1897, 18% for males and 4% for females) rather than denationalization. Some Romanian historians claimed that a strong sentiment of frustration and resentment to the Russian control had started to appear before the beginning of World War I.