Crimean Border Government
During the Russian Civil War, the Germans, taking advantage of the situation, marched troops from Ukraine into Crimea in Apr/May 1918 and established a Crimean puppet government lead by General Maciej Sulkevich. The region remained under German "protection" until the Germans were defeated in WW1 and withdrew their forces in Nov 1918.
After the Germans left, the puppet government was quickly disposed by an Anti-Bolshevik regime called the Crimea Border Government, led by Solomon Krym, a Kariate Jew and a former member of the Crimea state senate.
Although Krym was well liked by the local populace, he had little real power. After the defeat of the Germans and Ottomans in the war, Allied forces sailed into the Black Sea taking various strategic ports. The French Navy landed in Sevastopol along with other Crimean ports. The Crimean Border Government relied on the French forces for stability as their presence kept the Red Army out of Crimea. Krym also approached the leaders of the White Army for support of the new government, however the leader of the White Forces in South Russia, General Anton Denikin did not trust Krym's loyalty to their cause.
The French withdrew from Sevastopol on 15 Apr 1919, and signed an armistice with the Bolsheviks. Within a few days, the Red Army took over Crimea and the Crimean Border Government collapsed. Solomon Krym and his officials evacuated Crimea to France.
The Red Army was soon driven out by Denikin in June, but that is another story.
The 50 kopeck stamp / banknote was issued early in 1919 by the Krym Crimean Border Government. However, while these stamps were issued for postage, their primary use was as currency.