In his book Wooden Churches - Travelling in the Russian North, it says that the churches are the few remains of thousands that were built all over Russia from the time of Prince Vladimir, who, on his conversion to Christianity in 988 'ordained that wooden churches should be built and established where pagan idols had previously stood.' The majority are clustered in the north-west corner, and bunched in certain areas like Leningrad, Vologda, Murmansk, and Archangel Regions and the Republic of Karelia.
Read more: http://www.dailymail.co.uk/news/article-2252364/The-lost-churches-Russia-The-abandoned-wooden-buildings-left-forgotten-forests.html#ixzz2GAqmPlVW