The reverse of the flag or banner attributed to the Makhnovist Insurgent Army by Ostrovsky in "Jewish Pogroms, 1918-1921". It is disputed whether this flag actually belonged to the Makhnovists, or to another Civil War era group in Ukraine, such as the Free Cossacks.
Own work, based on File:Black Army or Free Cossacks banner.jpg
Thespoondragon