The Brotherhood of Saints Cyril and Methodius was a short-lived secret political society that existed in Kiev, at the time a part of the Russian Empire.
The organization predated the Spring of Nations in Eastern Europe just by few years. Wikipedia
Founders: Mykola Kostomarov, Panteleimon Kulish, Mykola Hulak, and more
Founded: December 1845
Membership (1846): 13 (active); 100 (total)
Political position: Left-wing