The Lykov family of Russian Old Believers survived in isolation in the Siberian taiga for over 40 years before contact with the outer world in the late 1970’s. A Smithsonian article titled “For 40 Years, This Russian Family Was Cut Off From All Human Contact, Unaware of World War II ” presents a fine summary of their life in obscurity and thereafter, with photographs and bibliographical references.
Personal note: The 1992 book by Vasily Peskov titled Lost in the Taiga: One Russian Family’s Fifty-Year Struggle for Survival and Religious Freedom in the Siberian Wilderness was one of the first books reviewed when Hermitary launched in 2002: http://www.hermitary.com/bookreviews/taiga.html