Short answers, pulled from the story.
Bessarabia is a historical region in Eastern Europe covering 45,630 square kilometers, bounded by the Dniester river to the east and the Prut river to the west. About two thirds of Bessarabia lies within modern-day Moldova, with the Budjak region in southern Ukraine and a small area of the Chernivtsi Oblast in the north also belonging to the historic region.
The traditional explanation traces the name to the Basarab dynasty of Wallachia, who allegedly ruled the southern part of the region in the 14th century. However, linguist Dan Alexe argues the name is most probably of Iranian origin, derived from ba sar ab meaning "by the water" or "headwater", referring to the point where the Danube flows into the Black Sea. The name first appeared in local sources only in the late 17th century.
The Russian Empire acquired Bessarabia through the Treaty of Bucharest, signed on the 28th of May 1812, which concluded the Russo-Turkish War of 1806-1812. The Ottoman Empire ceded the land between the Prut and the Dniester rivers to Russia, and the territory was organized as the Bessarabia Governorate. The acquisition was among the Russian Empire's last territorial gains in Europe.
The Kishinev pogrom took place in Chișinău, the capital of Bessarabia, on the 6th of April 1903. Local newspapers incited violence against Jews, with the anti-Semitic publication Bessarabetz, run by Pavel Krushevan, falsely alleging that Jews had murdered a Russian boy. The pogrom killed 47 or 49 Jews, severely wounded 92 more, and destroyed 700 houses.
On the 26th of June 1940, the USSR issued a 24-hour ultimatum to Romania demanding the immediate cession of Bessarabia and Northern Bukovina under threat of war, backed by the Molotov-Ribbentrop Pact's secret annex which placed Bessarabia in the Soviet sphere of interest. Romania yielded and the Moldavian Soviet Socialist Republic was formally established on the 2nd of August 1940 on most of the territory.
The Republic of Moldova declared independence on the 27th of August 1991, inheriting unchanged the boundaries of the Soviet Moldavian SSR. This preserved the existing partition of Bessarabia established in 1940: about two thirds remained in Moldova and smaller portions in northern and southern Bessarabia remained in Ukraine.