1) Basarabia declared independence from Russia after the October Revolution in 1917 and union with Romania in March 1918, becoming a Romanian province for 22 years. 2) In June 1940, the Soviet Union issued an ultimatum demanding Bessarabia, which Romania ceded, leading to its occupation by the Red Army. 3) The Treaty of Bucharest in 1812 had placed part of Moldavia east of the Prut River under Russian rule, dividing the region's identity between pro-Romanian and pro-Moldovan concepts promoted by Russia.

1. Prof: Mihai-Daniel Frumuselu Stud: Cristina-Emilia Ardeleanu
Bucharest, 2018

2.  Basarabia (as it was defined in the tsarist administration in
1812 to the Treaty of Bucharest) was constituted as a
Moldovan Democratic Republic at the end of 1917,
proclaiming its first autonomy in the Russian Republic, then,
after the Revolution of October, independence from Russia
Bolshevik and, after a few months, on March 27 / April 9,
1918 the union with the Kingdom of Romania, within which
it constituted a province. This state lasted for 22 years until
June 28, 1940 when a Soviet government ultimatum aimed at
implementing the Hitler-Stalin pact was addressed to
Romania demanding the cession of Bessarabia to the Soviet
Union. Romania ceded and after 48 hours Bessarabia was
occupied by the Red Army, the administration and the
Romanian Army retreating, in a dramatic chaos, to the west
of the Prut River.

3. 
By the Treaty of Bucharest in 1812, the part of the Moldovan
Principality, located at the East of the Prut, entered the empire of
Russia. From that moment, for the inhabitants of this region
formed the Basarabian rule, two opposing identity concepts:
"românismul" promoting the political and cultural union of all the
speakers of East Romanic languages ​​regardless of the kingdoms
whose subjects they were (the Habsburg Empire, the Empire
Russia, or the Ottoman Empire), and the "Moldovanism"
supported by the Russian authorities, which promoted the cultural
and political distinction and partition of East Romani speakers
subjected to the "Czar of All Russia" by the others. The union of
Bessarabia with Romania, voted on 27 March (9 April) 1918 by
the Councils of the Country (the Parliament of the Moldovan
Democratic Republic) represents the concretisation and victory of
the "Romanian" movement in this region.

4.  On July 16, 1917, the Central Committee of Chisinau decided to
establish a provincial council (after the Soviets model), which would
issue a bill for national and territorial autonomy. On September 4th,
this committee published its own newspaper, the Romanian Soldier,
with director Iorgu Tudor. At the same time, the Ukrainian National
Assembly decreed that Bessarabia is part of Ukraine, which led to the
Moldovans' request for protection of the Russian Provisional
Government in Petrograd. In detail, in a note of 16/29 March 1918 of
the Ukrainian authorities it appeared that in the northern part of the
territory of Bessarabia, Ukrainians live, and in the south (between the
mouths of the Danube and Nistru and the Black Sea coast) they have a
relative majority . Between 23 and 27 October 1917, the Council of
State proclaimed the autonomy of Bessarabia and the formation of the
council of the country as a legislative body. 44 deputies from the
ranks of the soldiers were elected, 36 peasants from the peasants, 58
deputies elected by municipal commissions and provinces and
professional associations. Of the 156 deputies, 105 were Moldovans,
15 Ukrainians, 14 Jews, 7 Russians, 2 Germans, 2 Bulgarians, 8
Gagauz, 1 Polish, 1 Armenian and 1 Greek.

5.  Lloyd George, the chairman of the Supreme Council of the Peace
Conference in Paris (Supreme Council of Clémenceau, Wilson, Lloyd
George and Vittorio Emanuele Orlando), communicated to Alexandru
Vaida-Voevod, the President of the Romanian Council of Ministers on
March 3, 1920, Romanian has demonstrated its willingness to resolve
suspended issues in the interest of Romania and Europe in general, allied
governments believe that the Bessarabian issue should no longer remain in
suspension. The Note of the Supreme Council states that "after taking into
account the general aspirations of the Basarabian population, the
Moldovan character of that province from a geographic and ethnographic
point of view, as well as the economic and historical arguments, the main
allied powers pronounce for these reasons in favor of the reunification
Bessarabia with Romania, a reunion that was officially proclaimed by the
representatives of Bessarabia ... " The Treaty for the Recognition of the
Union of Bessarabia with Romania was signed on 28 October 1920 in Paris
by the Council of Ambassadors of the British Empire, France, Italy and
Japan, on the one hand, and Romania, on the other

6.  . This Treaty recognizes Romania's sovereignty over the
Bessarabian territory, which includes the Prut, Nistru, the old
border of Bukovina and the Black Sea. Article 9 of the Treaty states
that the contracting parties will invite Russia to accede to this
Treaty as soon as there is a Russian government recognized by
them. Thus, the details of the Bessarabian reconnaissance
agreement were to be established through direct negotiations
between Romania and Russia. The treaty was ratified by the main
signatories: England, France and Romania. Italy and Japan have
not ratified the Treaty. Russia has maintained the attitude of not
recognizing the act of union. Neither the direct talks with Russia
at that time have yielded any result. In 1925, for the first time, a
Romanian delegation composed of Langa-Răşcanu, Drăghicescu,
M. Djuvara and others. met in Vienna with the Soviet delegation
led by Krestinski. Since the first contact, the Russians have put the
issue of Bessarabia in such a way that the Romanian delegation
has had to refuse the discussion and the conference has been
dissolved without any results. (Kiriţescu, 1989, op. Cit.).

8.  https://ro.wikipedia.org/wiki/Unirea_Basara
biei_cu_Rom%C3%A2nia
 https://www.historia.ro/sectiune/general/art
icol/unirea-basarabiei-prima-treapta-spre-
idealul-romaniei-mari
 http://enciclopediaromaniei.ro/wiki/Unirea_
Basarabiei_cu_Rom%C3%A2nia