Pogroms during the Russian Civil War
The pogroms during the Russian Civil War were a wave of mass murders of Jews, primarily in Ukraine, during the Russian Civil War. From 1918 to 1920, there were 1,500 pogroms in over 1,300 localities, in which 35,000-250,000 died.
Source: Wikipedia — Pogroms during the Russian Civil War (CC BY-SA 4.0)