With the Act of Union of March 1918, the regional parliament (Sfatul Țării) decided the union of Bessarabia with the Kingdom of Romania.
At first it was a conditional treaty, which preserved the autonomy of the region, but after the unconditional union of Bucovina in November 1918, Bessarabia was annexed completely.
The union was recognized by the United Kingdom, France, and Italy, in the 1920 Treaty of Paris (1920). These document come from the National Archives of Romania, The National Historical Central Archives, Președinția Consiliului de Miniștri, ds. 34/1918, f. 1.
March 27th, 1918
The Act of Union – by which the regional parliament (Sfatul Țării) decided Bessarabia’s union with the Kingdom of Romania. First, it was a conditional union (keeping the autonomy, included), but after the unconditional union of Bucovina (November, 1918) they dropped out of conditions. The union was recognized by the United Kingdom, France and Italy in the Treaty of Paris (1920).

The ethnological map of Bessarabia, drawn by Alexis Nour, based on russian and german maps and bessarabian local authorities statistics.

Ion Inculeț, the President of Sfatul Țării, the regional parliament of Bessarabia.

The members of Sfatul Țării, the regional parliament of Bessarabia.

March 30th, 1918 – Iassy. King Ferdinand and Queen Mary celebrating the Union of Bessarabia with Romania.

April 9th, 1919. The law by which Ferdinand, King of Romania, enacts the Union of Bessarabia.