Reddit reviews The Last Apocalypse: Europe at the Year 1000 A.D.

Sorry, I kind of simplified - i both read them in a book and read accounts in the library at the museum where i work and don't remember the author of those/i was reading those because they were getting moved to storage.

The book i originally read is The Last Apocalypse which is about how in about a 50 year timespan around the first millennium christendom went from almost getting wiped off the map (vikings, muslims, magyars) to converting scandinavia, forming christian kingdoms in poland and hungary, converting much of russia under vladimir the great, pushing the muslims out of italy and the fall of the biggest enemy, the umayyad caliphate in spain.

its quite a good read and focuses on not being completely accurate history but telling both what we know and what legends say to provide a full picture of not only the events but the people involved. The author calls it an apocalypse because not only the writers of the time thought it was but because this survival and expansion of Christendom was such a dramatic change in history.