A Russian and Czech medieval timeline by kasumigenx. What if the Kievan Rus christianizes earlier, via the help of Bohemia ? You can read it here.
The Author of this TL invites people to adopt this timeline and continue it.
Olga of Kiev was able to convince her son, Sviatoslav to convert to Christianity in 960 and because of that Sviatoslav marries Doubravka of Bohemia.